Corals dying

[Delphinus]

Sounds totally plausible to me..

Might not be an issue in this case but something to think about as well as that a zero PO4 reading isn't always "really zero."

Early on it was claimed with biopellets that they reduce PO4 as well as NO3. However, this has not been my experience (I do use and have used pellets on tanks and have seen good NO3 reduction or elimination with them. But not PO4.) It's been claimed more recently that they can only reduce PO4 as long as they have NO3 to reduce. Unfortunately I can't claim any anecdotal evidence to support or dispute that, so that may well be the case for all I know, but ultimately, regardless if that is true or not, pellets do have a limited ability to remove PO4. So even with pellet use, having GFO on the tank is a good idea.

It's been a while since I've done my reading on this, but if you go back over the years of reef chemistry postings by Randy Holmes-Farley and others, I think you can find more info, but from what I recall: basically you have organic phosphate and inorganic phosphate. We can only test for inorganic phosphate, we can't test for organic phosphate, but it's only organic phosphate we need concern ourselves. So we test the inorganics and hope for the best that there is a proportional relationship between the two. This might not always be the case. So basically unless you have something proven in place for PO4 removal (GFO or lanthanum or whatever), you might have PO4 even if you test it out and get a zero (or nominal) reading. So even if you think PO4 isn't a problem, having GFO (or similar product) on the tank regardless, is a good idea.

(I just wish GFO was cheaper...)

[Seriak]

Okay,

But I heard the correlation goes both ways. If you don't have enough phosphates, bio pellets will not be able to reduce nitrates and since I have high nitrates and supposedly low phosphates, I was thinking I didn't want to run GFO until my nitrates came down. I hope to pick up my GFO from Eli soon, but I wasn't going to use it until my nitrates levels were closer to 0. Should I start it up earlier?

[asylumdown]

If the bacteria in the biopellets are really using nutrients according to the redfield ratio, they use 16 times less phosphorous than nitrogen. You can have very low Phosphate levels and still have nitrate reduction taking place in your pellets. If you're really worried, you should start with a very small amount of GFO so that the levels don't plummet to zero in a few hours (that's good practice anyway).

[Seriak]

Originally Posted by asylumdown

If the bacteria in the biopellets are really using nutrients according to the redfield ratio, they use 16 times less phosphorous than nitrogen. You can have very low Phosphate levels and still have nitrate reduction taking place in your pellets. If you're really worried, you should start with a very small amount of GFO so that the levels don't plummet to zero in a few hours (that's good practice anyway).

Yeah, but if I have 0.02 to 0.03 Phosphates atm and >25 Nitrates (which could mean 100 for all I know) I would almost like to increase my phosphates in the short term to reduce my nitrates faster. Or at least I think I do.

[Madmak]

I ran a small amount of GFO with my pellets right from the start. It brought both Nitrates and Phosphates down quite gently and evenly.

It does take time though.

[Delphinus]

Maybe just hold off on the gfo for now and monitor the NO3. If it looks like it's coming down, leave it as-is but maybe once it gets to 10 or so (I'm just pulling this number out of the air arbitrarily) then go ahead and put the GFO on.

[asylumdown]

Originally Posted by Delphinus

Sounds totally plausible to me..

Might not be an issue in this case but something to think about as well as that a zero PO4 reading isn't always "really zero."

Early on it was claimed with biopellets that they reduce PO4 as well as NO3. However, this has not been my experience (I do use and have used pellets on tanks and have seen good NO3 reduction or elimination with them. But not PO4.) It's been claimed more recently that they can only reduce PO4 as long as they have NO3 to reduce. Unfortunately I can't claim any anecdotal evidence to support or dispute that, so that may well be the case for all I know, but ultimately, regardless if that is true or not, pellets do have a limited ability to remove PO4. So even with pellet use, having GFO on the tank is a good idea.

It's been a while since I've done my reading on this, but if you go back over the years of reef chemistry postings by Randy Holmes-Farley and others, I think you can find more info, but from what I recall: basically you have organic phosphate and inorganic phosphate. We can only test for inorganic phosphate, we can't test for organic phosphate, but it's only organic phosphate we need concern ourselves. So we test the inorganics and hope for the best that there is a proportional relationship between the two. This might not always be the case. So basically unless you have something proven in place for PO4 removal (GFO or lanthanum or whatever), you might have PO4 even if you test it out and get a zero (or nominal) reading. So even if you think PO4 isn't a problem, having GFO (or similar product) on the tank regardless, is a good idea.

(I just wish GFO was cheaper...)

This is exactly why I take all my test kits with a grain of salt. My test kits have all read 0.00 phosphate and nitrate for months, and yet my coral and coraline algae still grows, there's some hair algae in my overflows that still grows, and I still need to clean the glass every day or so. When you enter in to a situation where all your nutrients are either in a form you can't test for, or they're dynamically taken up by something the second they're produced, you almost need to rely on what your tank is telling you than what you get from a test kit.

[reefwars]

Originally Posted by asylumdown

This is exactly why I take all my test kits with a grain of salt. My test kits have all read 0.00 phosphate and nitrate for months, and yet my coral and coraline algae still grows, there's some hair algae in my overflows that still grows, and I still need to clean the glass every day or so. When you enter in to a situation where all your nutrients are either in a form you can't test for, or they're dynamically taken up by something the second they're produced, you almost need to rely on what your tank is telling you than what you get from a test kit.

your getting 0.000 on the ultra low test kit?

[asylumdown]

hanna for phosphates show 0.00 always, and Red Sea Nitrate kit with the little colour wheel has never had a colour change. I'm not sure if that's the ultra low range kit though, there's obviously some there in trace levels for things to still be growing.

Is there a kit that tests at a lower range?

[asylumdown]

Originally Posted by Delphinus

Maybe just hold off on the gfo for now and monitor the NO3. If it looks like it's coming down, leave it as-is but maybe once it gets to 10 or so (I'm just pulling this number out of the air arbitrarily) then go ahead and put the GFO on.

yah I think this is the best advice. 0.02-0.03 phosphate isn't bad, actually some people strive for that level.

The pellets take a while to do their thing.