Salifert PO4 Tests zero but algae still growing

[Jyetman]

Why do they sell the color chart kits if there not reliable? If my salifert test isn't showing any color does this mean I still may have to much phosphates in my water column?

 

[Randy Holmes-Farley]

Why do they sell the color chart kits if there not reliable? If my salifert test isn't showing any color does this mean I still may have to much phosphates in my water column?

In terms of algae growth, the absolute value of the phosphate doesn't matter as much as the flux of phosphate into the algae. A lot of rapidly growing algae will suck up phosphate just like growing macroalgae or an ATS are intended to do.

FWIW, many algae do not become phosphate limited until the phosphate is below 0.03 ppm. So depending on how well you can read 0.01, 0.02 and 0.03 ppm, the kit may not be adequate if the goal is to determine if the phosphate is limiting the growth or not.

 

[Jyetman]

In terms of algae growth, the absolute value of the phosphate doesn't matter as much as the flux of phosphate into the algae. A lot of rapidly growing algae will suck up phosphate just like growing macroalgae or an ATS are intended to do.

FWIW, many algae do not become phosphate limited until the phosphate is below 0.03 ppm. So depending on how well you can read 0.01, 0.02 and 0.03 ppm, the kit may not be adequate if the goal is to determine if the phosphate is limiting the growth or not.

So as long as the hair algae and macro is growing like crazy the soft corals shouldn't suffer from lack of phosphates?

 

[bertoni]

That'd be my guess. I think something else is more likely to be the cause of the coral problems.

 

[Randy Holmes-Farley]

So as long as the hair algae and macro is growing like crazy the soft corals shouldn't suffer from lack of phosphates?

That would be my expectation, yes.

 

[Jyetman]

That'd be my guess. I think something else is more likely to be the cause of the coral problems.

Could it be I'm starving the corals for years I just fed once a day. Started feeding three to four times a day just before thanksgiving and today everything is looking way better brain corals are more puffier even the zoos are starting to open more. One colony is almost completely open now.

 

[bertoni]

More food might be encouraging expansion. I'd just watch for signs of overfeeding, and others keep up with the new schedule.

 

[Jyetman]

Its been a month with increased feeding nearly tripled the feeding time! The corals are now about 25 percent better. Stupid kole tang always skinny other fish fat. Really don't understand this one zoa colony had fully opened but a week later started to partially close again. The green zoas still remain half open. No algae outbreaks in display tank only in the scrubber bucket and it has exploded with growth. My salifert PO4 kit still reads absolutely zero. All other parameters in the green and stable.

 

[bertoni]

You could consider an algae clip for the tang. I'm not sure why the soft corals are sulking.

 

[SantaMonica]

The periphyton and algae on your rocks probably was keeping the nutrients away from the zoo's. Zoo's just don't have the photosynthetic ability to match, and thus loose the battle to get the nutrients. More feeding usually fixes this, and creates a large flow of nutrients going to your scrubber as you saw. Just like on a reef, except there the flow is much larger because of the giant amounts of seaweed and phyto sucking up nutrients.

Test kits are not of much use; the standing value of P does not really matter. It's mostly the flow that matters.