In attempt to find another way to reduce both phosphates and nitrates as Vodka Dosing, ZEOvit Basic System, and other husbandry practices changes did not meet goals set for my system, began using N/P Reducing Bio Pellets as soon as they became available in the United States. It is a new and currently unproven system which is proposed to reduce both nitrates and phosphates as a better means than other carbon based systems.

The N/P reducing bio pellets are a solid based carbon source which does not dissolve in salt water which then limits the carbon dispersal to other parts of aquarium. Instead it forms a medium for beneficial bacteria to grow in one controlled location which then will consume available nitrates and phosphates in the water column. The theory is it eliminates the limiting of available carbon therefor nitrates and phosphates would become limiting when an adequate bacterial colony forms to consume all available nitrates and phosphates. The great part about this system, the pellets only need to be replenished every six to twelve months as needed instead of daily dosing which the other carbon based systems require.

The Plan

• Utilize a TLF Reactor to place 300 ml of N/P Reducing Bio Pellets and a Maxi Jet 900 to tumble the pellets
• Place the output hose for the reactor in front of the skimmer to help export the sloughed bacteria
• Increase or decrease quantity of N/P Reducing Bio Pellets based on results
• Supplement ZEObac or other bacteria source – add 0.1 ml/week
• Weekly water changes (3 – 5 gal) using Reef Crystals Salt
• Replace Granular Activated Carbon (GAC) every 15 – 30 days
• NOTE: Dosages are based on 25 gallon total system.

Goals

The following are goals to determine success:

• Reduce and maintain nitrate levels near zero
• Reduce and maintain phosphate levels at 0.03 ppm or lower without the use of GFO
• Improve coral health and colors

Hypothesis

The N/P Bio Pellets form medium for nitrate and phosphate reducing bacterium to grow in one location instead of throughout the aquarium which then reduces free form nitrate and phosphate levels in the water column without the problems associate with uncontrolled bacterial blooms found in other carbon based dosing systems. The bacterium then is exported through skimming and coral uptake.

Observations and Information

• 2009/11/23 — Began using 300 ml N/P Reducing Pellets in a TLF Reactor for my nano.
• 2009/11/23 — Began phasing out ZEOvit Basic System.
• 2009/11/23 — Nitrates 17.6 ppm, Phosphates 0.09 ppm.
• 2009/11/29 — Nitrates 17.6 ppm, Phosphates 0.03 ppm.
• 2009/12/05 — Nitrates 17.6 ppm, Phosphates 0.06 ppm.
• 2009/12/12 — Nitrates 17.6 ppm, Phosphates 0.04 ppm.
• 2009/12/30 — Nitrates 17.6 ppm, Phosphates 0.03 ppm.
• 2010/01/03 — Stopped using ZEOvit Basic System.
• 2010/01/17 — Nitrates 17.6 ppm, Phosphates 0.07 ppm.
• 2010/03/07 — Nitrates 8.8 ppm, Phosphates 0 ppm (Elos PO4 Test Kit).
• 2010/03/07 — NOTES: Up to 1/17, was performing 5% weekly water changes. Did not make water change until after today’s water tests to determine if impacted results. Not conclusive, but interesting. If it were not for starfish dying and decomposing on my week long trip last week, I would assume my nitrates may have been even closer to zero.
• 2010/06/09 — Nitrates 0.0 ppm, Phosphates 0.27 ppm.
• 2010/06/20 — Reinstalled GFO Reactor.
• 2010/07/03 — NOTES: The pellet tumbling has become a problem as slowed to non existent tumbling of the pellets. Rinsing pellets has helped but not near tumbling when first installed. Ordered the Algae Free Sure Flow 1600 Max-Jet upgrade kit to upgrade the flow in the Maxi-Jet 900 to 1600 gph. Hoping this does the trick as not a fan of the Maxi-Jet 1200 power draw versus performance increase. Not sure if it will do the trick as appears may require the shroud and will not work with stock attachment. Update 2010-07-12: I should have went with my instincts on this. The shaft is too long and can not be modified.
• 2010/07/05 — Nitrates 0.0 ppm, Phosphates 0.05 ppm.
• 2010/08/04 — NOTES: I have still been working on my problem where the pellet tumbling has become a problem as slowed to non existent tumbling of the pellets. It appears the pellets are very efficient at growing the beneficial bacterial colonies as my nitrates have dropped to zero. I believe they are what is causing the pellets to start sticking or “gluing” together. I can rinse the pellets so the brown film is almost off and they will tumble good for a couple days. Then they slowly build up this film and stop tumbling. I am out of options for putting a larger pump because I have limited space. I did upgrade from Maxi-Jet 900 to a Maxi-Jet 1200 but did not solve the problem.

  My LFS recommended trying one of the newer pellet brands as they are smaller in size and are suppose to tumble more and eliminate the problem I am having. They also recommend I replace my TLF Phosban 150 with the NextReef BioReactor which is designed for them and do much better job tumbling them. Will proceed trying different alternatives starting with easiest and cheapest first.

  First, start by chopping my current Bio Pellets into smaller pieces, observing, and then making determination on what to try next if it did not solve problem. Options after this still available, try cramming the Tunze 1073.020 pump in sump area (Cardiff, Salona sister, nano tank), NextReef BioReactor, or drilling tank to equip with a real sump and upgrade all equipment which may include the tank.

• 2010/08/05 — NOTES: Used the food processor to reduce my current Bio Pellets to half the original size, reinstalled reactor, and saw no significant improvement. Did do a much better job cleaning pellets which are shinny white again.

  Going to try the Tunze Recirculation Pump/Powerhead Silence 1073.020 which will produce up to 634 GPH at 30 watts with dimensions of 4 1/2″ x 2 3/4″ x 3 3/4″ which is similar to the Maxi-Jet 1200 up to 295 gph at 20 watts and dimensions of 3.5″ L x 2″ W x 3.25″ H. Based on measurements, should fit in compartment two where currently have the Maxi-Jet installed. Current selling price is $81.75 but out of stock or limited quantity at all the major online retailers. Going to be a few weeks/months before purchasing.

• 2010/10/03 — Nitrates 0.0 ppm, Phosphates 0.03 ppm.
• 2010/10/03 — NOTES: Have not switched out the pump to the reactor and still clumped together but appears to be still working based on the numbers.

Using Lamotte Nitrate test kit and Hanna Low Resolution Phosphate Photometer (accuracy ±0.04 mg/L, ±4% of reading) unless otherwise noted.

Conclusions

To be determined as my experiment is still in progress.

DISCLAIMER: Your results may very as each system is very different from another. For my tank parameters and environment, this was my observations and conclusion. This was not a controlled experiment so there is a potential for a very large margin of error. I would like to see some good scientific experiments on the subject.

References

Adams, Jake. “ULNS Is a Load of Detritus: an Ultra Low Nutrient ‘System’ is a Desert.” ReefBuilders. 29 October 2009. http://reefbuilders.com/…./. Accessed 15 March 2010.

Hessen, Dag O., Thomas R. Anderson. “Excess carbon in aquatic organisms and ecosystems: Physiological, ecological, and evolutionary implications.” Limnol. Oceanogr., 53(4), 2008, 1685–1696. American Society of Limnology and Oceanography, Inc. http://www.aslo.org/lo/toc/vol_53/issue_4/1685.pdf. Accessed 10 May 2009.

Holmes-Farley, Randy. “Phosphate and the Reef Aquarium.” Reefkeeping Magazine. September 2006. http://reefkeeping.com/issues/2006-09/rhf/index.php. Accessed 12 May 2009.

“ULNS Is Not Really L and Far From UL.” Grumpy Old Reefer. 28 October 2009. http://grumpyreefer.net/…./. Accessed 15 November 2009.

I began using Chaetomorpha (pronounced “kay-toe-morf-a”) macro algae (Chaetomorpha spiralis) today for nutrient exporting as I am taking a new approach and attacking my Nitrate issue from multiple fronts which I have blamed for driving my Algae issue. I have already went bare-bottom, reduced volume of live rock, increased and improved flow, implemented ZEOvit system after trying Vodka dosing, reduced feeding after selecting the best food to use with minimal impact on nutrients, and upgraded skimmer.

I bought and installed a Current PowerBrite 10,000K Daylight LED Lighting System brick in the middle chamber where I placed a handful of chaeto. I chose chaeto over caulerpa as it is less likely get sucked into the pumps or spread throughout the sump through sexual reproduction. The downside it is a slow grower and traps detritus. I will need to be careful as it grows in a ball with outer portions receiving light with an increased likelihood the portion in middle dying off and then releasing the nutrients back into the water column. To help alleviate this, I will rotate the chaeto weeky and export extra as needed.

I will ensure I follow a good photo period regime to allow for proper photosynthesis process and respiration during dark period. I have read to maintain a photo period of 16 hours on followed by 8 hours off so not to stimulate reproduction cues for the algae usually triggered by shortening of photo period. Some argue it does not matter and run their refugium’s lights 24/7. So I can take advantage of the pH buffer benefit, I will have chaeto photo period alternate with my display tank photo period.

The Goal

• Nitrates below 4.4 ppm using LaMotte Test Kit
• Phosphates below 0.03 ppm using Low Phosphate Hanna Meter
• Improved SPS Coral Health
• No negative impacts on system

Hypothesis

Chaetomorpha absorbs nitrates and phosphates from the water column as its natural biological process which then can be exported by removing a portion of the Chaetomorpha on a regular cycle thus reducing overall free form nitrates and phosphates.

Observations & Notes

2009-12-02: Removed some of the Chaeto ball as appears I have had some growth. I expected more growth but believe I am not because my nutrients are finally limiting. I have not needed to scrape the glass in a week and it is still clear, bacterial bloom seems to be non existent, algae near undetectable, and coral health has been improving.

Nitrates still tested at 17.6 ppm and Phosphates at 0.03 ppm on Sunday but feel still elevated as the bacteria and algae have been dying and collecting in piles on the bare-bottom requiring me to siphon out a couple times last week. This has stopped as not much more left so I expect to finally see an additional decline in detectable nutrient numbers when I test this weekend.

2009-12-05: Nitrates tested at 17.6 ppm and Phosphates at 0.06 ppm. Disappointed as I expected to see a positive impact by now.

2010-01-03: I am not seeing much growth from the Chaeto even though Nitrates still at 17.6 ppm and Phosphates 0.03 ppm. I am believing the lighting is the issue as should be providing a light in the range of 2300K to 9600K spiral compact fluorescent bulb at 26w. Will need to explore purchasing a clip on fixture and bulb.

Conclusions

Experiment still in progress.

DISCLAIMER: Your results may very as each system is very different from another. For my tank parameters and environment, this was my observations and conclusion. This was not a controlled experiment so there is a potential for a very large margin of error.

References

Borneman, Eric. “Mything the Point: Part Two.” Reefkeeping. December 2003. http://www.reefkeeping.com/issues/2003-12/eb/index.php. Accessed 17 November 2009.

“Chaetomorpha.” Wikipedia. 12 October 2009. Wikimedia Foundation, Inc. http://www.liu.edu/cwis/cwp/library/workshop/citmla.htm. Accessed 17 November 2009.

Riddle, Dana. “A Different Look at Lighting: Effects of Prolonged Photoperiod, Spectral Quality, and Light Dosage.” Advanced Aquarist’s Online Magazine. May 20009. Reefs.org Publications. http://www.advancedaquarist.com/2009/5/aafeature. Accessed on 26 November 2009.

Schwartz, Gene. “A Warning Sign of Impending Caulerpa Sporulation.” Reefkeeping. May 2004. http://www.reefkeeping.com/issues/2004-05/nftt/index.php. Accessed 17 November 2009.

I have been struggling with nitrates for the last six months and have been battling algae for a couple months (see War! The Algae Must Die!!). Frustrated as I can not determine the source of the problem and not sure what to do now, I have decided to attack the problem with a multi approach strategy using every method available to me. What I have done this far:

• Reduced feeding to point I lost a couple fish and LPS heads are receding or dying.
• Stopped feeding for week and Nitrates still maintained at 26.4.
• Changed feed to a Rod’s Original Blend and ELOS sv.M2 to minimize nutrient addition. Use minimal amount to keep fish and LPS alive (5-10 ml Rod’s 50% diluted with H20 spot feed to LPS, 6-8 pellets ELOS, alternating days).
• Tried Vodka dosing. Protocol did not work for me for some reason.
• Tried ZEOvit system and still using with final determination pending.
• Changed skimmer to Euro Reef Nano Skimmer and then Sapphire Aquatics Solana / Cardiff Skimmer.
• Every other day 5% water changes for two weeks. Dropped Nitrates to 17.6 but jumped back to 26.4 in a week.
• Tried different LaMotte test kits with same results.
• Use GAC
• Use RODI. TDS at zero. Nitrates test zero. Change pre filters every six months. Membrane only one year old.
• Tried AlgaeFix Marine
• Regular blowing DT live rock with powerhead to help export build up of detritus
• Regular stirring and siphoning of sand bed to help export build up of detritus
• Increased clean up crew quantity and diversity
• Change filter floss one to two times a day

Coral health has been a concern as I have been losing some Acros along the way which I have been tending to blame the nitrate levels as all other parameters have been in check. Some of my Acros have been growing good and assume they are hardier. When I am feeding the LPS properly, they are thriving but I have lost a few with my attempts to minimize nutrients into the system. Both my leather and zoas are growing great. For last several months, I have not added any new corals to the system as I want to be a good caregiver and hate to lose one much less the many I have lost in last few months.

The baffling point is the Nitrates stay at 26.4. I even tried over feed for several weeks to track impact. Stayed at 26.4. Phosphates maintain at 0.01 to 0.03. Can not figure it out so I am now blaming too much live rock and poor circulation as I am running out of what to blame for the Nitrate issue.

Today, I removed 10 pounds of live rock, changed the rock configuration, and added two of my old Tunze Turbelle Nanostream 6025 Powerheads back into tank along with the EchoTech MP-10 Wave Maker / Powerhead already installed. This was a major undertaking as I had to remove the majority of my corals and reattach. The new layout should create better flow and less dead spots. Time will tell if this will help drive down nitrates.

Update 2009-11-07: Removed Sand Bed and Going Bare-Bottom

In my fight to reduce Nitrates, I removed the sand bed today and going bare-bottom. I have some reluctance to go this route as I love the look of a sand bed and reviewed good articles from some highly respected hobbyist who say a deep sand bed is key to a successful system. I like what I have read about the advantages for a SPS dominated tank being able to increase flow without worrying about sand storms. This was a major undertaking as you can imagine with some preplanning needed for the sake of the livestock I have in the tank already.

First task, start draining tank into an 18 gallon Rubbermaid tub. As soon as the water was to an appropriate level, I started to move all rock work, corals, fish, and invertebrates to the Rubbermaid tub which I placed next to the tank. Third and should have been first task, changed settings on ReefKeeper Elite so only the EchoTech MP-10 and the lights are powered as they have been moved to the tub. Once I got the tank drained and the back chambers drained, I started task of removing the sand bed.

It was amazing how half the sand bed had solidified into one big chunk and what I believe has been the cause for my on going battle with nitrates. Using a kitchen knife, I had to carefully pop the chunks up from the bottom of the tank so not to crack the tank. Once I got the all the solid chunks out, I then scooped out the rest of the loose sand bed using a small bowl and finished with a shop vac to finish the job.

I then cleaned and dried the bottom of the tank getting it ready for a piece of clear acrylic which I had cut to size using the Cardiff’s glass top as a template and modifying as necessary. Many just go bare bottom without anything else added to bottom but I wanted to protect the bottom from rock slides and I did not like the looks of the white PTFE or Starboard others placed in bottoms. I then used silicone to caulk around the acrylic so not to have detritus make its way under and advised by LFS as their starfish have made their way under their Starboard.

After waiting for the silicone to dry for 12 hours, I began filling the tank putting a little in to determine if there were any leaks. I had to make a decision as my craftsmanship seems to not have been up to par as there were a couple leaks back in the rear corners. Do I redo my work or live with it and what undetermined side affects will I have with water between the acrylic and glass? Time will tell as I went with knowing water will seep between the two and over period of time coralline algae will grow over the bare-bottom as I have seen with other reefers with bare-bottom tanks. I do not expect any detrimental side affects and have not read of any issues as I assume most do not silicone their installations. Disappointed, yes, as I like the mirror affect where the water has not seeped between the two pieces yet.

After making the decision to live with the water between the glass and acrylic, I filled the tank using the water I saved from emptying it and another five gallons for what the sand bed had displaced. Took a bit of time to get the rock work back in place and stable as the sand bed had allowed for minor adjustments. After a couple hours, seems to be success with everything back in and running. Now time will tell was this worth the work and I will I see a positive impact on my nitrates and corresponding improvement in coral health.

Observations & Information

Update 2009-11-15: A Week Later Observations

The look is growing on me but would have been better without the leak between the two as the mirror affect is cool but disappearing as the water creeps its way between the two. Initially, my phosphates spiked to 1.0 ppm using Hanna Meter Low Phosphate test kit which I was told to expect and then dropped to 0.04 ppm by this weekend. My Nitrates initially dropped and maintained at 17.6 ppm using LaMotte test kit. I am happy with both numbers and expect my SPS corals to show the same which I will use a frag purchased this weekend as my test to coral health as the frag came from a good tank and has not been stressed in my tank. I would not have done this last test if I was not confident I finally got this nailed down.

My Sapphire Skimmer has been back ordered as the manufacturer was modifying the alloy mesh wheel they were using which was disintegrating in matter of months which I was not aware was an issue. My current skimmer, the Euro Reef Nano, three times this week was skimming great with a half cup of skimmate and then next time I looked at it a few hours later had dumped it all back in when it started to blow its cup for no reason. I can’t wait to get this piece of crap off my tank as the problems with needing to adjust and clean the sponge every day outweigh the skimming performance. It is too bad as it does skim great.

One interesting observation, I have not had to scrape algae of my glass all week.

Update 2009-11-20: Two Weeks Observations

It is real easy to clean the tank and I can turn the power heads full blast so in this aspect it has been worth the change as long as coral health or chemistry does not deteriorate. The nitrates have maintained at 17.6 ppm. In my opinion, it is still too early to tell if any of the changes are having an impact as I assume my chemistry was disrupted as I removed a good amount of biological processes which had established itself which will require others to take hold.

My assumptions from removing live rock and sand bed which increases flow and decreases stored nutrients while continuing to limit nutrient addition: less stored nutrients = reduced algae and bacteria populations = less or slowed nutrient conversion = current detectable nutrient levels fluctuates either up or down until biological process reestablish balance = current detectable levels decrease to near undetectable levels by minimizing nutrient addition. The first assumption, less stored nutrients, is highly debated wether the removal of the sand bed improves or worsens the biological processes to convert nitrates to harmless components.

Update 2009-11-30: Three Weeks Observations and Notes

I have been actually putting off writing these observations in fear of jinxing myself as I am a bit superstitious even with my science background says it is a bit crazy. I have to say, I think I am winning the battle with my GHA, cyanobacteria, and bacteria outbreak as their populations have declined dramatically and near undetectable. I have also noticed some growth and good polyp extension from some of my SPS. My nutrients are still at 17.6 ppm for Nitrates and 0.03 ppm Phosphates but attribute this to the adjustment my beneficial bacterial are making for the removal of the sand bed and the break down of the dying GHA, cyano, and bateria.

As above and the following can attest, I am throwing absolutely everything at the problem which I have researched which may be a solution including the following added in last week as they have been proposed as potential solutions to nutrient issues:

• Reduced my feeding habits even more
• Added chaetomorpha to center chamber along with 10,000K LED lighting to light opposite from DT lighting
• Added N/P Reducing Biopellets to an additional reactor
• Increased my magnesium to 1600 using Kent Marines Tech M Magnesium
• Added some more clean up crew (6 x Trochus Snails) to replace the ones which have died
• Replaced the Euro Reef Nano Skimmer with Sapphire Aquatics Skimmer
• Upgraded T-5 lighting to MH
• Siphoned any detritus build up twice a week (easy to see and siphon being bare-bottom now)
• Upgraded my 5 stage RO/DI system to a 7 stage system (5 micron sediment filter, 1 micron sediment filter, 1 micron ChlorPlus 10 Carbon Block, 0.6 micron MATRIKX® +1 Carbon Block, and 2 DI Resin Canisters). Will need to watch pressure to membrane to make sure not too many stages causing too large drop in pressure to the membrane and DI.

The chaeto has not started to grow yet and the N/P Reducing Biopellets are still forming their own beneficial bacteria colonies so too early to see their benefits.

Downside to performing everything at once, I will never really know what one contributed to resolving my issue while others were only antidotal. I will have to say, I really don’t care if it permanently solves my problems. I believe from what I have read about other’s experiences and information from other web sites, it is a multi facetted approach which is needed when you do have an outbreak.

Update 2009-12-15: Five Weeks Observations and Notes

Algae and bacteria bloom almost undetectable which I am very happy about as best my tank has looked in months. Coral health improving with the best growth and coloration I have seen in my tank. Chaeto seeing a little growth but not much. Nitrates still at 17.6 ppm and phosphates at 0.04 ppm. Lost my yellow coris wrasse today and will not know for sure but blame reducing food too much. I am back to feeding every day in small amounts (Alternating days between 5 – 8 Elos SV. M2 pellets and 4 ml Rods Reef) and will back off to every other day if see nutrients increase.

So far my observable results from a multi approach strategy has been the best plan instead of trying one or two things at a time. I assume I will see a reduction in nitrates and phosphates in near future once the algae and bacteria die off has been fully exported from system resulting in a net decrease in nutrients.

Conclusions

A multi method approach is key to success:

• Limit nutrient addition
• Provide one or more means to export nutrients through natural, mechanical, and chemical processes
• Provide appropriate lighting to deter algae growth
• Utilize a good cleaning routine
• Limit sources where nutrients are stored
• Monitor and control water column chemistry
• Include algae chemical regime (AlgaeFix, Tech M Mg) if necessary and know the risks associated with each
• Finally and most important when you do have an algae outbreak, be patient if you are utilizing every method mentioned as part of solution as the problem did not start overnight and will take as much time or longer to correct the problems

Only attacking the problem with a couple methods, will limit your success and the majority of the time result in failure. What differentiates a novice reef keeper and a experienced reef keeper who can maintain great reef tanks are they understand and utilize every method available and appropriate for their reef tank.

DISCLAIMER: Your results may very as each system is very different from another. For my tank parameters and environment, this was my observations and conclusion. This was not a controlled experiment so there is a potential for a very large margin of error.

References

Borneman, Eric. “The Old Becomes New, Yet Again: Sandbeds and Vodka.” Reefkeeping Magazine. October 2004. http://www.reefkeeping.com/issues/2004-10/eb/index.php. Accessed 20 November 2009.

Borneman, Eric. “The Old Becomes New, Yet Again: Sandbeds and Vodka, Part II.” Reefkeeping Magazine. November 2004. http://www.reefkeeping.com/issues/2004-11/eb/feature/index.php. Accessed 20 November 2009.

Fellman, Scott. “From revolution to evolution: a look at two hobby trends and their impact.” Reef Builders. 20 November 2003. http://www.reefbuilders.com/2009/11/20/revolution-evolution-hobby-trends-impact/. Accessed 20 November 2009.

Holmes-Farley, Randy. “Chemistry and the Aquarium.” Advanced Aquarist’s Online Magazine. August 2003. http://www.advancedaquarist.com/issues/august2003/chem.htm. Accessed 20 November 2009.

I am seeing good coral growth and coloring and attribute to the ZEOvit system. Using my Red Planet Acro as baseline which has its red color and green base back. The ORA Roscoe’s Blue Acro has nice blue base color back with nice green polyp coloring and growth. I did lose my Orange Hammer LPS coral which was my favorite coral. I believe I damaged it when I accidently bumped it with another coral which cause it to recede and have STN. My Frogspawn and Torch LPS corals are growing like crazy.

I am still having issues with nutrients (35.2 ppm Nitrates and 0.03 ppm Phosphates) but only one full month into using the ZEOvit rocks. I need to be patient with protocol. I changed the ZEOvit rocks in the reactor and will proceed with the ZEOvit protocol I have for my tank.

I am seeing green hair algae or cyno starting to take hold in more areas of tank with the maintained nutrient levels. I am looking into using AlgaeFix Marine as I am reading good things about it over at Reef Central.

I am seeing my Alkalinity needing to be dosed 10 to 20 ml daily to maintain the proper level even with dosing Kalkwasser as part of top off. Both calcium and magnesium are inline. Will need to continue to closely monitor to determine if change in tank. I did verify with a newer test kit to eliminate the test kit as the issue.

For some reason I started losing my Turbo Snail, Florida Turbo (Astraea tecta) about two weeks ago. Out of the 18 I had, I am down to eight. I am not sure why unless the ULNS has impact on them with not enough food for them to survive.

It has been argued one food source is better than another at contributing minimal nutrients to our closed reef systems. I want to determine which is better based on Nitrate and Phosphate levels of each.
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