Phosphates

[lduncan]

Yip, so basically the media has held onto the orthophosphate until bacteria grab it to use and convert to organic phosphate.

So how is it going to de-saturate pools of organic phosphate?

[wasp]

Well firstly, it's only you saying the bacteria will "grab" or " steal" the phosphate from the media.

I didn't say that, and the manufacturer would also dissagree.

How will it remove bound phosphate? It won't. At least not directly.

In practise though, it will eventually deplete phosphate by grabbing it whenever it changes form, as it is constantly doing.

[lduncan]

Spontaneously changing form? You know it's the bacteria which is driving the change a lot of the time. They actively, and directly liberate bound P by secreting enzymes like alkaline phosphatases. They are more than capable of literally stealing it from the media.

The manufacture is saying that in sterile conditions, once the media has bound P it will not release it again. Which is more or less true. That's the chemistry approach. But as soon as you introduce bacteria, that becomes irrelevant. They can still get it, they have to be able to.

Then there are biofilms which can create environments which chemically "dissolve" P precipitates. They have a few different was of liberating P from seemingly "inert" substances.

The bacteria are driving almost all the changes in P states in the tank. If they want it, they can almost always get it.

Layton

[wasp]

The manufacture is saying that in sterile conditions, once the media has bound P it will not release it again.

Layton

That's not what I saw the manufacturer say.

[lduncan]

That's what they mean. I'm giving them the benefit of the doubt here. If they truly meant exactly what they said when the product is used in it's intended environment, they would be wrong.

Even the manufacturer of one particular brand of phosphate remover is aware of these phosphate grabbing organisms. Here he talks about algae, which can do similar death defying feats with bound phosphate:

For algae as a nutrient it does not matter if it is inorganic ortho-phosphate or it is an organic phosphate ester.

Although they can't take up the organic phosphate, they will excrete an enzyme to transform it to, for them bio-available, ortho-phosphate.

They will only do this if the ortho-phosphate concentration in the water is extremely low.