Concept question about GHA and phosphates

tmnails

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Thanks in advance for your time!

Quick system info:
-220 gallon, 3 gallon daily auto water change
-Large working skimmer and fleece roller
-Feeding 2 cubes daily, occasionally pellets and reef roids
-Half dozen small fish (trying to figure thread topic out before adding more)
-Kessil 360x's, and T5's
-Lots of flow

Question(s):
Do we know how aggressively GHA out competes corals for phosphates? If I'm struggling to get measurable phosphates, but have an algae turf scrubber successfully growing thick green hair algae, is it really just as simple as turning the scrubber off? If someone is struggling to raise phosphates, would it be sound advice to give up on algae reactors or chaeto balls in general (if they have a working skimmer, fleece roller, other export)?

More Context:
I've been struggling to get measurable phosphates for almost 2 years with this system. Just coming off of another GHA bloom in my display, and have always had a big sheet of it on my waterfall ATS. Lately if been dosing neophos, broadcasting reef roids and adding pellets in an attempt to raise phosphates, but I'm still reading 0.00 on an ultra low hanna checker.
 
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tmnails

tmnails

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I don’t know that green hair algae does out compete corals, given exactly equivalent situations.
Hey Randy!

Would you recommend turning off the ATS all the same? I'm growing a full sheet of dark, thick GHA but my corals seems to be struggling. PH between 8.1 and 8.3, nitrates 15-20, everything else is in a decent range, but my phosphates stay bottomed out.
 
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Randy Holmes-Farley

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Hey Randy!

Would you recommend turning off the ATS all the same? I'm growing a full sheet of dark, thick GHA but my corals seems to be struggling. PH between 8.1 and 8.3, nitrates 15-20, everything else is in a decent range, but my phosphates stay bottomed out.

If you think the corals are needed more N and/or P (a reasonable hypothesis), then reducing the lighting time on the algae or feeding more both seem good options.
 

92Miata

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Thanks in advance for your time!

Quick system info:
-220 gallon, 3 gallon daily auto water change
-Large working skimmer and fleece roller
-Feeding 2 cubes daily, occasionally pellets and reef roids
-Half dozen small fish (trying to figure thread topic out before adding more)
-Kessil 360x's, and T5's
-Lots of flow

Question(s):
Do we know how aggressively GHA out competes corals for phosphates? If I'm struggling to get measurable phosphates, but have an algae turf scrubber successfully growing thick green hair algae, is it really just as simple as turning the scrubber off? If someone is struggling to raise phosphates, would it be sound advice to give up on algae reactors or chaeto balls in general (if they have a working skimmer, fleece roller, other export)?

More Context:
I've been struggling to get measurable phosphates for almost 2 years with this system. Just coming off of another GHA bloom in my display, and have always had a big sheet of it on my waterfall ATS. Lately if been dosing neophos, broadcasting reef roids and adding pellets in an attempt to raise phosphates, but I'm still reading 0.00 on an ultra low hanna checker.
My experience with these things is that it isn't really that the GHA outcompetes the corals - it's that the whole tank becomes phosphate deficient, and complex organisms aren't capable of utilizing carbon and nitrogen without phosphorus. So you bottom out on the phosphates, corals, coralline, etc, stops growing, and nitrates start rising.

Then you get these simple archaic organisms like cyano and dinos and such that are really good at living in these edge conditions - and they flourish because they have means of capturing phosphate or nitrogen when the normal forms aren't present in the water column - and they have a smorgasbord of trace/etc because the corals aren't growing. GHA - for instance, collects crud - even in high flow. That crud breaks down in the GHA, creating local areas of phosphate and nitrogen availability, and that crud breaking down creates acidic microenvironments, dissolving tiny surface areas on the rock and releasing phosphate.

There's no real reason to struggle dosing phosphates - just dose more. When you're dealing with tanks that are really deficient, you often need to dose A LOT before things stabilize at measurable levels. Dose the tank to .03-04, wait 24 hours and see where it is. Dose it to .03 again. If it drops the same amount, get a dosing pump and dose that amount daily. Check every couple days and back down if it gets above about .06.
 
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