How to raise nitrates and lower phosphates?

[rishma]

I have a 13.5 and used GFO to deal with a phosphate spike I was having. It does not take much at all and I’d recommend underestimating rather than over. I accidentally wiped mine out to 0 in 2 days. Took it out and haven’t had issues since.

Funnily enough, I’m having the opposite issue of you now, nitrates are slightly high but my phosphates are bottomed out so it’s looking like I’ll be dosing for it.

This is a common experience with GFO in small tanks. I finally figured out that using ~1/5 the recommended amount as a starting point worked pretty well for my small tank and didn’t strip the phosphate too fast. I still had to test frequently. When phospate stopped declining, I would add a little more, not swap out for a full fresh batch of GFO. It took time, but sloooow and steady is better when reducing phosphate in my experience.

 

[EastonsReef]

I have a 13.5 and used GFO to deal with a phosphate spike I was having. It does not take much at all and I’d recommend underestimating rather than over. I accidentally wiped mine out to 0 in 2 days. Took it out and haven’t had issues since.

Funnily enough, I’m having the opposite issue of you now, nitrates are slightly high but my phosphates are bottomed out so it’s looking like I’ll be dosing for it.

This is a common experience with GFO in small tanks. I finally figured out that using ~1/5 the recommended amount as a starting point worked pretty well for my small tank and didn’t strip the phosphate too fast. I still had to test frequently. When phospate stopped declining, I would add a little more, not swap out for a full fresh batch of GFO. It took time, but sloooow and steady is better when reducing phosphate in my experience.

I definitely learned my lesson. The hobbyists who advised me had never kept nanos. Luckily no lasting harm was done

 

[allenk4]

Are you suggesting it’s not? I don’t see how tank size matters. But if there’s a reason to prefer sodium nitrate dosing, that’s fine too.

Not suggesting anything, just asking the question. Seems like with such a small volume of water, GFO may not have a large margin of error?

Wouldn’t water changes would be simpler and have less potential risk?

 

[Randy Holmes-Farley]

Not suggesting anything, just asking the question. Seems like with such a small volume of water, GFO may not have a large margin of error?

Wouldn’t water changes would be simpler and have less potential risk?

Well, it did not seem like “just a question” when you quote someone’s advice and ask if it’s the best option. It’s more like a suggestion that it is not. Presumably they think it’s a good option.

But this is not about GFO. In my question to you, I was quoting your asking whether the ammonia dosing was the best option for boosting N, not the GFO issue (at least that is the post you quoted in your question ). Small tank size does not make ammonia dosing less (or more) desirable. It can be easily and safely done on any scale.

But that said, water changes are not generally a great way to reduce phosphate since even a 100% change may not bring it down enough due to binding and then release from rock and sand. In a very small tank, a number of water changes can get there, but other methods may be less tedious or expensive.

 

[allenk4]

Well, it did not seem like “just a question” when you quote someone’s advice and ask if it’s the best option. It’s more like a suggestion that it is not. Presumably they think it’s a good option.

But this is not about GFO. In my question to you, I was quoting your asking whether the ammonia dosing was the best option for boosting N, not the GFO issue (at least that is the post you quoted in your question ). Small tank size does not make ammonia dosing less (or more) desirable. It can be easily and safely done on any scale.

But that said, water changes are not generally a great way to reduce phosphate since even a 100% change may not bring it down enough due to binding and then release from rock and sand. In a very small tank, a number of water changes can get there, but other methods may be less tedious or expensive.

Interesting. Where can I find more information about phosphate binding in a reef aquarium environment?

 

[Randy Holmes-Farley]

Interesting. Where can I find more information about phosphate binding in a reef aquarium environment?

I’m not sure what level of article you want, but if you want to dig into the mechanism of binding, i discuss it here:

Phosphate In The Reef Aquarium
https://www.reef2reef.com/blog/?p=3184

from it:


A second mechanism for potential phosphate reduction when using high pH additives is the binding of phosphate to calcium carbonate surfaces. The absorption of phosphate from seawater onto aragonite is pH dependent, with the binding maximized at around pH 8.4 and with less binding occurring at lower and higher pH values. Habib Sekha (owner of Salifert) has pointed out that limewater additions may lead to substantial precipitation of calcium carbonate in reef aquaria. This idea makes perfect sense. After all, it is certainly not the case that large numbers of reef aquaria exactly balance calcification needs by replacing all evaporated water with saturated limewater. And yet, many aquarists find that calcium and alkalinity levels are stable over long time periods with just that scenario. One way this can be true is if the excess calcium and alkalinity, which such additions typically add to the aquarium, are subsequently removed by precipitation of calcium carbonate (such as on heaters, pumps, sand, live rock). It is this ongoing precipitation of calcium carbonate, then, that may reduce the phosphate levels; phosphate binds to these growing surfaces and becomes part of the solid precipitate.

If the calcium carbonate crystal is static (not growing), then this process is reversible, and the aragonite can act as a reservoir for phosphate. This reservoir can inhibit the complete removal of excess phosphate from a reef aquarium that has experienced very high phosphate levels, and may permit algae to continue to thrive despite all external phosphate sources having been cut off. In such extreme cases, removal of the substrate may even be required.

If the calcium carbonate deposits are growing, then phosphate may become buried in the growing crystal, which can act as a sink for phosphate, at least until that CaCO3 is somehow dissolved. Additionally, if these crystals are in the water column, e.g., if they form at the local area where limewater hits the aquarium water, then they may become coated with organics and skimmed out of the aquarium.

If phosphate binds to calcium carbonate surfaces to a significant extent in reef aquaria, then this mechanism may be attained with other high pH additive systems (such as some of the two-part additives, including Recipe #1 of my DIY system). However, this potential precipitation of phosphate on growing calcium carbonate surfaces will not be as readily attained with low pH systems, such as those using calcium carbonate/carbon dioxide reactors or those where the pH is low due to excessive atmospheric carbon dioxide, because the low pH inhibits the precipitation of excess calcium and alkalinity as calcium carbonate, as well as inhibiting the binding of phosphate to calcium carbonate.

 

[allenk4]

I’m not sure what level of article you want, but if you want to dig into the mechanism of binding, i discuss it here:

Phosphate In The Reef Aquarium
https://www.reef2reef.com/blog/?p=3184

from it:


A second mechanism for potential phosphate reduction when using high pH additives is the binding of phosphate to calcium carbonate surfaces. The absorption of phosphate from seawater onto aragonite is pH dependent, with the binding maximized at around pH 8.4 and with less binding occurring at lower and higher pH values. Habib Sekha (owner of Salifert) has pointed out that limewater additions may lead to substantial precipitation of calcium carbonate in reef aquaria. This idea makes perfect sense. After all, it is certainly not the case that large numbers of reef aquaria exactly balance calcification needs by replacing all evaporated water with saturated limewater. And yet, many aquarists find that calcium and alkalinity levels are stable over long time periods with just that scenario. One way this can be true is if the excess calcium and alkalinity, which such additions typically add to the aquarium, are subsequently removed by precipitation of calcium carbonate (such as on heaters, pumps, sand, live rock). It is this ongoing precipitation of calcium carbonate, then, that may reduce the phosphate levels; phosphate binds to these growing surfaces and becomes part of the solid precipitate.

If the calcium carbonate crystal is static (not growing), then this process is reversible, and the aragonite can act as a reservoir for phosphate. This reservoir can inhibit the complete removal of excess phosphate from a reef aquarium that has experienced very high phosphate levels, and may permit algae to continue to thrive despite all external phosphate sources having been cut off. In such extreme cases, removal of the substrate may even be required.

If the calcium carbonate deposits are growing, then phosphate may become buried in the growing crystal, which can act as a sink for phosphate, at least until that CaCO3 is somehow dissolved. Additionally, if these crystals are in the water column, e.g., if they form at the local area where limewater hits the aquarium water, then they may become coated with organics and skimmed out of the aquarium.

If phosphate binds to calcium carbonate surfaces to a significant extent in reef aquaria, then this mechanism may be attained with other high pH additive systems (such as some of the two-part additives, including Recipe #1 of my DIY system). However, this potential precipitation of phosphate on growing calcium carbonate surfaces will not be as readily attained with low pH systems, such as those using calcium carbonate/carbon dioxide reactors or those where the pH is low due to excessive atmospheric carbon dioxide, because the low pH inhibits the precipitation of excess calcium and alkalinity as calcium carbonate, as well as inhibiting the binding of phosphate to calcium carbonate.

Thank you for taking the time to respond in such detail and the link. Very informative.

I wonder if this is what happened to Reef Bum when a large portion of his substrate hardened into a solid mass?

I also wonder if this can be avoided by dosing Kalk to the overflow, as far upstream of the display tank as possible and by pausing dosing when Powerheads are in feed mode?