Adding nitrate to reduce phosphate

[E30Adam]

I currently run a 150gal SPS ZEO system, nitrates have come down to an undetectable level but I can't get my PO4 to reduce. It fluctuates between 0.03 and 0.05. Coral colouration is good but I'd like to reduce my PO4 to a lower level.

As my system is bacteria driven then the redfield ratio applies. In order for bacteria to remove phosphate then nitrate must be present. As my nitrate is undetectable then the bacteria cannot remove any more phosphate which is why i believe that I can't reduce my phosphates.

I currently run a PO4 reactor but media is very expensive and I don't want to continue this way. I also don't want to increase fish stock or feeding as this will also increase my PO4 which will be counterproductive.

So, has anyone had any experience of adding Nitrate to their system. I know there are various methods and chemicals that can be added.
Sodium Nitrate
Calcium Nitrate
Potassium Nitrate

I'm thinking that calcium nitrate might be a good option because it will also add calcium to my system. I'm running the balling light system to keep alk, mag and cal in check so I can always adjust my calcium balling dosing to maintain a correct calcium level if I'm adding calcium via calcium nitrate as well.

What are your thoughts and or experiences with this.

Many thanks.

[HighlandReefer]

"It fluctuates between 0.03 and 0.05."

I assume you are using a meter of some sort to claim detection between 0.03 - 0.05 phosphate. There are a lot of threads where the accuracy of the hobby grade meters is in question and some meters can be off by 0.03 ppm. If you are running GFO properly and replacing it at proper intervals, your phosphate should be lower than 0.03 ppm or you need to change it out more frequently.

[E30Adam]

I should have mentioned, I've been using the new Hanna Phosphorus checker to monitor my PO4 and I'm also using a D&D Merck kit which confirms the results.

I use 250ml's of Rowaphos in a reactor and it's changed monthly. If I increase the amount of GFO I use then it's going to cost me a small fortune. It's very expensive here in the UK.

I already have the bacterial system to do the job if I add the nitrate. This would cost me a lot less than keep changing out GFO media and with the added bonus of not having to run the reactor.

[Percula9]

Try ordering from www.bulkreefsupply.com. Its much cheaper than rowaphos.

[ChuckG]

Adam,

I run Zeo and have tried my hand with this when the tank seems nitrogen starved.

http://www.seachem.com/Products/product_pages/FlourishNitrogen.html

Note that this does not just add nitrate but also ammonium which boosts total nitrogen levels. This might be better than adding just potassium nitrate.

If you try this start very slow.. On a lightly loaded 75G I dosed 0.1ml twice a day to the zeo Rx for 10 days or so.. then bumped it up to 0.2ml twice daily until I saw some pink (0.2mg/l N03) in a salifert nitrate test. Once you see pink the tank should no longer be nitrate limited and you can stop dosing to see how long the reading persists. Best to go very slow and develop a feel for this while monitoring NO3, PO4, and any algae growth to see if it will help reduce the dependence on PO4 removing media. Eventually you should be able to get off PO4 removers entirely. This could take some time if the PO4 is bound to the rocks and substrate though.

BTW I believe, although not sure, that sponge power is supposed to provide some form of nitrogen as well.

[E30Adam]

Chuck, thank you for your input. This is exactly the sort of information I'm looking for.

Were you dosing Nitrate for the same reasons as me and did you find it was successful?

Eventually I would like to take my PO4 reactor offline completely. I think that dosing a small amount of NO3 a day will work out much cheaper than buying GFO.

[bertoni]

I'd check with the manufacturer to see whether the ammonium will stay bound up in saltwater. A few people have reported success adding nitrogen.

[ChuckG]

Chuck, thank you for your input. This is exactly the sort of information I'm looking for.

Were you dosing Nitrate for the same reasons as me and did you find it was successful?

Eventually I would like to take my PO4 reactor offline completely. I think that dosing a small amount of NO3 a day will work out much cheaper than buying GFO.

I could never really measure N03 or P04, but prefer riding the edge of P04 limitation vs. N03. That said, 0.02mg/l is not a lot of N03 but still more than a zero reading. Every tank could react differently so go very slow and observe if you try this.

Really all this will do theoretically is speed up the consumption of your P04 reserves slightly. This could still take some number of weeks, months, or years dependent on history and age of your substrate and rocks. Your just making the process more efficient by insuring nitrogen compounds (not just nitrate) are not a limiting factor.

Also you might check with the zeo heads about cycling your Rx on and off every three hours with a timer. I think the off/anaerobic cycle might help process PO4 more efficiently as well. You need to make sure water stays in the Rx during the off cycle so the stones don't go dry.

EDIT: Also you want to take a close look at how much PO4 you actively import on a daily basis. It might help to cut back on frozen foods if you feed a lot of them, or simply rinsing thouroughly in RO/DI can help. Nori can add alot of PO4 so cutting back on its use can help too. Lastly there are some dry fish foods that contain less PO4 than typical, more balanced anyway.. of these ELOS makes one that I use and trust.

[ChuckG]

I'd check with the manufacturer to see whether the ammonium will stay bound up in saltwater. A few people have reported success adding nitrogen.

Hi Jonathan.. I don't suspect all the ammonium maintains the ionic bond and will break down to toxic ammonia pretty quickly after being added to the high PH saltwater. That is one of the reasons I say to use very little at a time.

Also we probably want to be careful not to spike any one nutrient in the system and add things like this very slowly so the beneficial bacterial colonies can catch up to the added load. Spikes in nutrient levels seem to favor the more unfavorable consumers like cyano and others.

I think of using this product in very small doses like adding the urea waste of a larger fish but without all the additional PO4.

[E30Adam]

Thanks again for your input Chuck.

I'm very careful with importing PO4 and want to keep it at an absolute minimum and for this reason I don't feed frozen food. I only feed my fish once a day and I feed them the New Era flake foods, marine flake, aegis 1 and aegis 2 on their rotation scheme. All fish seem happy and nourished so I don't feed them any more than this. I also keep a very close eye on the RO that I use. I won't use it when the TDS reaches 1 and at this point I'll change out my DI resin.

Of course, whatever I dose, I'll do it very gradually and keep a very close eye on the results.

It's an interesting point you make about the 3 hour on/off cycle with the Zeo RX. I'll put a post up on the zeo forum and see what they say about it. As the RX is in my sump, the stones remain under water when the RX goes off.

[E30Adam]

Thanks again for your input Chuck.

I'm very careful with importing PO4 and want to keep it at an absolute minimum and for this reason I don't feed frozen food. I only feed my fish once a day and I feed them the New Era flake foods, marine flake, aegis 1 and aegis 2 on their rotation scheme. All fish seem happy and nourished so I don't feed them any more than this. I also keep a very close eye on the RO that I use. I won't use it when the TDS reaches 1 and at this point I'll change out my DI resin.

Of course, whatever I dose, I'll do it very gradually and keep a very close eye on the results.

It's an interesting point you make about the 3 hour on/off cycle with the Zeo RX. I'll put a post up on the zeo forum and see what they say about it. As the RX is in my sump, the stones remain under water when the RX goes off.

[tmz]

just fyi, gfo can be regenrated. Saves $ ,been doing this for over a year and have used some brs HC gfo 10x over.

http://www.reefcentral.com/forums/showthread.php?t=1734717&highlight=regeneration+gfo

[Patio]

Great topic.

I am trying to learn more about this as I am showing similar NO3/PO4 readings. There are a few other related posts on RC that I will try and find links to. I hope this discussion flourishes.

I just stocked up on some more 2LF Phosban from my favorite online retailer (unsure if I am allowed to name drop) at a considerably lower price. However, I would love to be spending this cash on frags.

Kind of intimidating posting in the chem forum. lol.

[tmz]

Keep posting,plenty of room for more thoughtful insight and questions. Glad you are enjoying the discussion.

[Allmost]

Hello all,

why are you running po4 removers with Zeovit ?

let the bacteria take it up, the continual renewal of the po4 absorbers and ... are not helping the bacteria :)

[abrian]

Hello all,

why are you running po4 removers with Zeovit ?

let the bacteria take it up, the continual renewal of the po4 absorbers and ... are not helping the bacteria :)

I believe the OP was operating under the theory that he had reached zero nitrate and further bacterial reduction of po4 was therefore limited if I understood the discussion correctly.

[Allmost]

lol well yes I saw that ...

but, Zeovit bacteria will work and remove po4 and no3. in fact, if the method is used correctly, you should not have any po4 ISsues, as when the Zeoliths are cycling alot more po4 is removed from system than no3 is :)

Zeovit guide advices you against using GFO.

what I meant up there was, when GFO introduced, the 0.03 PPM of po4 will go down to zero within 12 hours or less ! and will raise after as the GFO is shut ....
this will give the Zeovit bacteria a updown of po4 which will UNABLE them to work correctly to remove both po4 and no3.

I run Zeovit for a long time on almost all my tanks, and no po4 Issues ! that's how the system is designed to work !
if you are dosing vodka and have po4 Issues then YES, GFO is needed. cause Vodka dosing doesnt export po4 that well :) Acetate acid does :) vineager.

just my 2c .... no3 limiting IMO is possible, but in Zeovit, if method is used correctly, it wont happen.
lastly, to add no3, u can feed fish more, or u can dose amino acids or .... they all break down to ammonia down the road ...

[tmz]

Why do you think bacteria that consume acetic acid consume more PO4 than those that consume ethanol? Or the bacteria on zeolites for that matter? Never saw anything to substantiate a variation in CNP consumption by microbes in anaerobic digestion.