Nitrate/Phosphate experiment.

[The Plantman]

I have a very interesting thing that has happened to my tank! I’ve been running an experiment to see how low a water change I can do while keeping my Nitrate below 5ppm. I started dosing with Aquacare Plant Nutrition two weeks ago. For the second week, Last sun 11th, I started dosing with said fertilizer that also included N03 and PO4. This has had a very strong reaction. Algae of several types including BBA on leaf tips (light), Green Spot on the glass and leaf surfaces and Blue Green in sheets on lower glass near substrate! I tested for NO3 and PO4 today, and showing for the first time in any of my tanks is a clear amount of Phosphate and virtually zero Nitrate. I have always shown a shortage of Phosphate (PO4). PO4 always being the limiting factor in plant growth in my aquariums. I assume.

I can only assume from this that Nitrate has become the tanks limiting factor, leaving a surplus of PO4, which seems to be bad!

I am going to discontinue using the fertilizer that included NO3 and PO4. Get my limiting factor back to PO4, I think. I hope when the tank starts showing virtually zero PO4 with a slight NO3 surplus the algae will start to die off. If it does, this could mean for my tank that excess PO4 causes far more algae then excess NO3.

green spot and just a bit of BBA

Blue green?

I did accidentally without thinking scraped some of the Blue green off the glass, you can see a line right at the edge of the gravel on the glass and the sheet that came off the glass fell onto the baby tears. I have never had blue green; it is very soft and slimy feeling.



The only other thing that has changed is, I am defusing the CO2 with my power head instead of putting it into the canisters. CO2 droped to 25ppm putting PH at 7.0. I had it going into a canister before and getting 30-35 and a PH of 6.8. I wanted to see how efficiently the power head would defuse Co2.

 

[Canuck]

I can only assume from this that Nitrate has become the tanks limiting factor, leaving a surplus of PO4, which seems to be bad!

Are you sure its not the lack of nitrates that is causing your problem? What about CO2? Seems you've leaped to the conclusion of PO4 being the problem without considering other hypothesis. The types of algae that you list are commonly attributed to nutrient deficiencies. BBA is commonly associated with inadequate or fluctuating levels of CO2. GSA is commonly associated with inadequate levels of PO4. BGA is commonly associated with low nitrates. Limiting nutrients as a strategy is only successful with low light set ups. And even then your riding the razor's edge. IME, provide excess amounts of all nutrients for the available light and you won't run into algae problems. Both my high light and low light setups get 30 ppm of nitrate, 3ppm of phosphates and ample traces every week. I've never had fewer problems with algae.

 

[The Plantman]

Are you sure it's not the lack of nitrates that is causing your problem?

As I stated in the post, yes I believe it is my lack of Nitrates and excess Phosphates that is causing the problem!

What about CO2?

The types of algae that you list are commonly attributed to nutrient deficiencies. BBA is commonly associated with inadequate or fluctuating levels of CO2.

I have been testing my CO2 every day for the past 2 months! It has been steady at 30-35ppm for the entirety of that time. Only when I change one of my two bottles every two weeks does it drop for little less then 24 hours to 15-20ppm. For a DIY setup I'd say that's pretty solid. Also, I've had no issues with algae for that entire time.

Seems you've leaped to the conclusion of PO4 being the problem without considering other hypothesis.

4 days before this happened, 3 things changed.

1) CO2 was dropped down to 25ppm from 30ppm, not really all that significant in my opinion. However, it is still a change and I understand it could be a contributing factor.

2) I switched from using Tropica Aquacare to Tropica Aquacare+N&P

3) for the first time ever in one of my tanks do I show an excess of PO4

GSA is commonly associated with inadequate levels of PO4. BGA is commonly associated with low nitrates.

As I stated in the post I currently have excess PO4 so this cannot be the cause of GSA. As well, I have been showing virtually zero PO4 for 2 months and 3 weeks without having any issues with plant growth. Not that I believed there hasn't been PO4 in the tank just that it has been to low for my store bought test kit to register.

I have been running low nitrates for 2 months without issue (5ppm to very low) I think possibly adding the supplemental NO3 and PO4 may have caused my Nitrates to run completely out while there still being significant Phosphate in the tank, possibly causing the algae bloom. Excess phosphate near zero Nitrates.

Limiting nutrients as a strategy is only successful with low light set ups. And even then you’re riding the razor's edge. IME, provide excess amounts of all nutrients for the available light and you won't run into algae problems. Both my high light and low light setups get 30 ppm of nitrate, 3ppm of phosphates and ample traces every week. I've never had fewer problems with algae.

This is good to know, the IE method does sound popular around here. After I finish this experiment, I will be trying the EI method.

 

[Canuck]

Please note, I'm not trying to dissuade you from what you're doing it all. My comments are made as constructive criticism. One thing you should note if it hasn't been mentioned before is calibrating your test kits. There are instructions at http://www.plantedtank.net/forums/f...83545-calibrating-test-kits-non-chemists.html . I'm still not absolutely clear on your hypothesis- I think your saying that if PO4 is greater then NO3 algae is the result, so would this be true if PO4 was 8 and NO3 were 5? I've never tried this so I'm not making suggestions at all. As far as your tank management, if the non-dosing is working then that's great, I'd probably stick with it too. EI isn't mandatory by any means. My question about the CO2 is based on the fact we work with hobby grade kits which are dependent on colour distinction. Personally, I'm never confident that I've matched the colour properly. Now that I have pressurized on my high light tank, I just leave it a little below where it bothers the fish.

 

[Canuck]

Based on your "studies". You might find the following link interesting. http://en.wikipedia.org/wiki/Liebig%27s_Law_of_the_Minimum

I do know EI works (among other methods), which in my opinion, really, all result in the same goal, healthy growing plants. I don't understand why healthy plants result in minimal algae but I have seen enough evidence to believe it as truth. I've also seen where struggling plants will result in algae outbreaks without fail. I know I can starve plants (I've done it), I've never been successful at starving algae.

Good luck with your experiments

 

[tackful]

I have never understood how a tank with healthy plants in nutrient laden water can have far less algae than a tank with zero nutrients in the water column. This is at the same time both true yet counterintuitive. Then I came across an article on plant allelopathy.
This concerns the process by which plants release chemicals that either benefit or inhibit the growth of their neighbors. Perhaps our healthy plants are somehow producing and releasing their own form of algaecide.

 

[The Plantman]

Please note, I'm not trying to dissuade you from what you're doing it all. My comments are made as constructive criticism. One thing you should note if it hasn't been mentioned before is calibrating your test kits. There are instructions at http://www.plantedtank.net/forums/f...83545-calibrating-test-kits-non-chemists.html . I'm still not absolutely clear on your hypothesis- I think your saying that if PO4 is greater then NO3 algae is the result, so would this be true if PO4 was 8 and NO3 were 5? I've never tried this so I'm not making suggestions at all. As far as your tank management, if the non-dosing is working then that's great, I'd probably stick with it too. EI isn't mandatory by any means. My question about the CO2 is based on the fact we work with hobby grade kits which are dependent on colour distinction. Personally, I'm never confident that I've matched the colour properly. Now that I have pressurized on my high light tank, I just leave it a little below where it bothers the fish.

No no, I'm not offended at all! I appreciate your questions and interest.

I think maybe that because I may have very near zero Nitrates with still phosphate in the tank, that algae has been the result. I think possibly that it would be a better situation for me to have an excess of Nitrate then of Phosphate.

 

[The Plantman]

I have never understood how a tank with healthy plants in nutrient laden water can have far less algae than a tank with zero nutrients in the water column. This is at the same time both true yet counterintuitive. Then I came across an article on plant allelopathy.
This concerns the process by which plants release chemicals that either benefit or inhibit the growth of their neighbors. Perhaps our healthy plants are somehow producing and releasing their own form of algaecide.

Very interesting thought! I have also questioned how a healthy planted tank with lots of excess nutrients can not grow algae.

I'm now trying to make Phosphate my limiting factor, while having an excess of Nitrates and all other nutrients by fertilizing without the use of extra N and P. I'll be adding more fish to increase bioload in order to increase Nitrates and feed with low phosphate foods in an attempt to keep Phosphates lower and have Phosphate be the first nutrient to run out.

 

[Canuck]

I'll be adding more fish to increase bioload in order to increase Nitrates and feed with low phosphate foods in an attempt to keep Phosphates lower and have Phosphate be the first nutrient to run out.

I'm afraid I think this may be a flaw. Extra fish will also impact plant (and algae) available ammonia and potentially increase other organics. There is a lot of evidence that ammonia is a key component of algae outbreaks. Note the number of posts citing algae problems in immature tanks (less then a year old IMO). While your test kits show 0 ammonia, this only means that the levels are lower then hobby kits can sense. If you have fish then you have a given amount of ammonia. A more scientifically rigorous experiment would be with inorganic fertilizers.

 

[The Plantman]

I'm afraid I think this may be a flaw. Extra fish will also impact plant (and algae) available ammonia and potentially increase other organics. There is a lot of evidence that ammonia is a key component of algae outbreaks. Note the number of posts citing algae problems in immature tanks (less then a year old IMO). While your test kits show 0 ammonia, this only means that the levels are lower then hobby kits can sense. If you have fish then you have a given amount of ammonia. A more scientifically rigorous experiment would be with inorganic fertilizers.

The tank has been up and running for over 2 years. It was originally a successful breeding Cichlid tank. I was able to control algae by using Phos-zorb, expensive but it did the trick. However, I got board of its non-evolving nature and decided to go back to a planted aquarium.

My first tank was a planted 29 gallon that was 95% algae fee. I did 20% water changes (without firts) every two weeks to maintain it for three years. It was a 2.4 watts per gallon, twin bottle DIY CO2 injected (25ppm), tetra tank, that had one 4 1/2in stripped Raphael cat and about 20 other 1 to 1 1/2in fish in it. I could never detect Phosphate in this tank. I'm sure it was there just in very low quantities.

In this 46gallon I'm attempting to aim for a similar thing, lots of macro/micro nutrients but having Phosphate as a limiting factor in growth or simply the lowest nutrient in the tank.