Do corals prefer orthophosphate?

[Miami Reef]

I read multiple posts here saying that metaphosphate or organic phosphate is what corals, mainly acropora, prefer, and that orthophosphate is a waste product that corals don’t prefer.

Is orthophosphate similar to nitrate where corals don’t really prefer it or have to work harder to use it?

 

[Randy Holmes-Farley Verified Community Expert]

A few comments on that...

The term prefer is a very complex issue here, unlike with nitrate.

1. I don't know where the metaphosphate idea comes from, but metaphosphate is a ring of three phosphate groups. It is reportedly very unstable in water, and thus is not something one would expect organisms to take up, or even be available to them. It is an intermediate (that is, a transient material) that can form when organisms break down polyphosphates, and perhaps that is the nugget of truth that leads to what I'd consider incorrect conclusions about metaphosphate being taken up.

2. With a few exceptions, the uses of phosphate by an organism will always go through orthophosphate. That is, orthophosphate is the molecule used to make organophosphates of all types. For example, in a huge process in vivo, three orthophospahtes are attached to a transfer molecule to make ATP. The ATP is used to drive all sorts of chemical reactions, resulting in ADP (two phosphates on the transfer molecule) plus orthophosphate (unless the chemical reaction attached the phosphate to something else). Then orthophosphate is reattached to make the starting ATP ready for another use.

3. Organic molecules that contain N and P are taken up by organisms for many uses, which include the organism's use of the whole organic itself, and the metabolism of the material to give energy or smaller useful molecules, including ammonia and orthophosphate. Thus, organisms taking up organics (including whole prey items such as bacteria or phytoplankton) will take in lots of phosphate this way.

If an organism is getting phosphate from consuming phytoplankton, does that mean it prefers plankton to orthophosphate? That's probably a semantic debate, but it may well be true that if you give an organism such as a coral all of the P it needs by giving it organic matter, that it may not take up much orthophosphate. I expect this effect is why corals in the ocean thrive at phosphate levels lower than in typical reef tanks: because there is not as much of the types of organic matter than they want to consume.

 

[Miami Reef]

Thank you so much, Randy! That helps clear things up.

My reef tank dropped to 0.0 ppm PO4, and I did some forum searches. I wanted to make sure the phosphate I dosed wasn’t just a waste product that wasn’t bioavailable. I wanted my corals to have the PO4 they deserved.

This makes me feel better knowing they now have a good source of phosphate. Thank you very much.

 

[Big E]

I use liquid P04 short term to establish a depletion rate daily and form a baseline. After that I use a natural product like Reefroids. This makes more sense to me than dumping liquid into the system.

In the end I prefer to add more fish for a natural cycle & what the corals need come from the fish waste and some that comes from my fish food mix.

My reasoning is that fish waste may also contain elements they don't use as well beyond P04 that also gets distributed.

 

[Randy Holmes-Farley Verified Community Expert]

I use liquid P04 short term to establish a depletion rate daily and form a baseline. After that I use a natural product like Reefroids. This makes more sense to me than dumping liquid into the system.

In the end I prefer to add more fish for a natural cycle & what the corals need come from the fish waste and some that comes from my fish food mix.

My reasoning is that fish waste may also contain elements they don't use as well beyond P04 that also gets distributed.

That’s certainly a reasonable plan, but the other things from more foods hypothesis work both ways, potentially adding something you do not want instead of just adding things you want.

 

[Big E]

That’s certainly a reasonable plan, but the other things from more foods hypothesis work both ways, potentially adding something you do not want instead of just adding things you want.

I make my own food and it's all raw seafood and some nori, so I know what goes in it. I feed that about 95% of the time. That other 5% or so is commercial mysis.

 

[Randy Holmes-Farley Verified Community Expert]

I make my own food and it's all raw seafood and some nori, so I know what goes in it. I feed that about 95% of the time. That other 5% or so is commercial mysis.

Yes, and so it adds lots of organics, nitrogen, and other things one may or may not want in all situations. :)

 

[Big E]

In my situation I want those organics. I can only speak for my own system and what I do. This is a fully mature system with many colonies. I don't run anything else but a skimmer.

So, it depends on where one is with the system they currently run.

 

[Miami Reef]

I think dosing up PO4 (from 0.0ppm) and then using fish and coral foods as a maintenance is a great balance between both methods.

I (very recently) started playing with different coral foods to get some extra coral growth. I’m trying the kitchen sink approach.

 

[Randy Holmes-Farley Verified Community Expert]

In my situation I want those organics. I can only speak for my own system and what I do. This is a fully mature system with many colonies. I don't run anything else but a skimmer.

So, it depends on where one is with the system they currently run.

Foods are certainly a fine plan if you know you want more of what they bring in. :)

 

[Big E]

I think dosing up PO4 (from 0.0ppm) and then using fish and coral foods as a maintenance is a great balance between both methods.

I (very recently) started playing with different coral foods to get some extra coral growth. I’m trying the kitchen sink approach.

I've done this more than once to maintain systems with no fish. The corals stayed alive but didn't thrive. Once fish were added it was like night and day.

Speaking only with Sps I don't believe coral foods have any benefit other than adding nutrients and elements.

It's fine you want to experiment but I've been there done that for years and my conclusion is the coral foods/amino acid supplements don't matter long term and in some cases become detrimental.

As always, with this hobby the old becomes the new. I don't know if your were around back then but the Italians came up with a "Pappone" feeding regime that claimed to make corals grow insanely fast. Now we have the concoction food from that one dude with a little twist by adding a carbon source.

If I wanted to improve growth my first thought would be to run lighting that mimics the sun's spectrum.

Honestly though, be careful what you wish for.................. fast growing corals become a problem. Great when you have frags but are a major hassle when they get too big.

 

[Miami Reef]

I've done this more than once to maintain systems with no fish. The corals stayed alive but didn't thrive. Once fish were added it was like night and day.

Speaking only with Sps I don't believe coral foods have any benefit other than adding nutrients and elements.

It's fine you want to experiment but I've been there done that for years and my conclusion is the coral foods/amino acid supplements don't matter long term and in some cases become detrimental.

As always, with this hobby the old becomes the new. I don't know if your were around back then but the Italians came up with a "Pappone" feeding regime that claimed to make corals grow insanely fast. Now we have the concoction food from that one dude with a little twist by adding a carbon source.

If I wanted to improve growth my first thought would be to run lighting that mimics the sun's spectrum.

Honestly though, be careful what you wish for.................. fast growing corals become a problem. Great when you have frags but are a major hassle when they get too big.

I’m confused. I have a lot of fish already. I feed LRS that is very similar to your DIY food.

When I said I’d feed coral foods, I meant foods like reef roids etc. I thought we’d be on the same page lol