Algae is taking over my tank!

[DownwardDawg]

My tank is almost one year mature now. It's a 125 gal tank. I started running my UAS a little over a month ago. The screen fills in nicely in about a week now and needs cleaning. I also grow chaeto in my refugium and it completely fills the refugium in about a week's time. I perform a 20 gallon WC once to twice a month, depending on my schedule. I run carbon but do not run any GFO. I use RO/DI water that reads 0.00ppm on my Hanna Checker. My T5 bulbs are ony a couple of months old but my halides are almost a year old. Here are pics of my scrubber after about 7 days of growth.

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The following are pics my wife took today.

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[SantaMonica]

Sounds like your scrubber and chaeto are working. Phosphate is coming out of the rocks.

[RkyRickstr]

Sounds like your scrubber and chaeto are working. Phosphate is coming out of the rocks.

Wasn't this proved scientifically impossible?

[Floyd R Turbo]

I wouldn't say it have been disproven, but rather that there is not a lot of evidence to support the "phosphate leeching" theory. There is not a lot of evidence to disprove it either. So far from what I can tell from leaning on others regarding the situation is that there are 2 possible scenarios.

In one, phosphate has precipitated into the structure of the rock. For this phosphate to be leeched out, a very low pH would have to be attained, around 7.2 or less, probably 7.0 or less. At this level, not many corals would survive for long. At high pH, 7.8-8.4, where our tanks should be, phosphate would not leech out of bonded structure - that is impossible. The only possibility is algae or bacteria or both creating a localized situation where the pH was lowered in order to 'access' the phosphate, but this action would also release compounds that would raise the pH back up, so this is not a viable scenario for algae taking over the tank. Though some have mentioned "soft" areas of their rock when the remove tufts of algae (not sure how to interpret that description)

In the other, phosphate is more or less 'sitting' on the rocks, in a detritus form, etc, not chemically bonded to the rock. These would be used up pretty quickly, not really a long-term problem.

IMO, the bottom line here is not enough growth on the scrubber. Let scrubber grow longer, and increase the flow as much as you possibly can.

[RkyRickstr]

I'm on the fence on this one. On one side I understand the arguments against it. But I had a tank with very high p for weeks. I removed half of the rock and it dropped and the scrubber for it on check. The leaching theory would explain it perfectly.