Nitrates, Phosphates, and Silica

[woochi]

This is probably a dead horse topic but a good one to keep beating lol
My goal for this post is to have as many people chime in on how Nitrates, Phosphates and Silica enter our tanks on a basic level and simple measures to prevent or control them. I'm doing this so new reefers and old can keep on top of this subject. Thanks in advance

 

[Randy Holmes-Farley]

They enter primarily in foods, unless you are using tap water, in which case top off can be a significant source, especially for silicate.

 

[Randy Holmes-Farley]

There are many good ways to reduce nutrients, including growing macroalgae, ATS, skimming, organic carbon dosing, denitrators, GAC, live rock, GFO and other phosphate binders, and more.

I use many of these together.

 

[woochi]

So the silica , I've been wondering if a certain algae feeds off it? Seems like some reefers may think they have a phosphate or nitrate issues and it's only silica

 

[Randy Holmes-Farley]

All algae need both N and P, but only diatoms also need silicate.

 

[woochi]

Interesting, so is there any odd or uncommon ways silica get in the system, like materials that a person may think is reef safe

 

[Randy Holmes-Farley]

Well, aside from the possibility of releasing silicates when silica sand is first added, or from foods or additives that contain it, I don't know of any.

It generally is rapidly depleted so isn't a concern in the absence of a big source.

FWIW, I dose silicate for sponges and other creatures that can benefit.

 

[woochi]

So by chance do you know how to tell if your gfo is spent, fully saturated?

 

[Randy Holmes-Farley]

Measure phosphate in the effluent and in the tank. If the effluent is not lower, it is spent.

At high phosphate, it will be spent quite rapidly.

 

[woochi]

I tested the discharge of the gfo reactor with Hannah phosphorous checker and I got 24 ppb ,then I discovered I was out of refents! Ha go figure. Btw I'm confused about the conversion to phosphate, is 24 ppb high for phosphorous?

 

[Randy Holmes-Farley]

That's a little high at about 0.07 ppm, and the tank may be higher.