Algae issues

[PhilOlsen]

I have a 55 FOWLER, it has been up and running for 5 years now and for the past few weeks the algae is out of control. All my LR (120 lbs) is covered with brown hair like algae, the substrate (sand) has got red and brown algae, even the powerheads have it.
I only use RO/DI water, the lights are 4 month old T5's (4 x 54 watt), I only feed every other day so overfeeding is not the issue. It has a SS65 skimmer, Aqua 25 watt UV, 2 MJ 1200 powerheads. Lights are on 8 hours a day.
I am really confused by this, params are same as they have been for years, no change in salt, salinity, anything except this algae outbreak that is out of control....

[PhilOlsen]

I even tried moving the rock but it got covered in about 4 days just like before it was turned.

[PhilOlsen]

Forgot about the stocking. It has a Humu Humu trigger, yellow tang, Perc. clown, yellow tail damsel and a stripped damsel.

[Cuby2k]

Bump this up because I have had similar issues and would like some constructive feedback/suggestions.

[cfarrow2]

PO4! You have phosphate issues that aren't going to show up on your test kits because it's being absorbed by your HA. I recommend lots of water changes and a refugium, if at all possible. Good luck cause I'm having my own fight with that crap. Biggest PITA I've ever seen.

[schigara]

WHat is the TDS of your RO/DI water? How often do you change your sediment, carbon and DI filters? When was the last time you changed the membrane and what gpd rating and brand membrane do you use?

[PhilOlsen]

TDS is 0, entire unit is 7 months old and is a 75 GPD unit. I do not have the issue in my other tanks using the same water, that is why it is driving me NUTS!!!!

[Avi]

My guess is that over the time that the tank has been going, the relatively large amount of rock that you have 120-pounds in a 55-gallon tank is a lot of rock) has collected detritus to the point that it's virtually saturated and now it is leaching phosphates into the water column that is supporting that aggressive algae growth. I'd increase the flow in the tank...and put at least one phosphate reactor on using a high-quality phosphate removing medium like Rowaphos or its equivalent and keep that medium replenished regularly. If you aren't seeing any elevated nitrates when you test then it's almost surely phosphates that are more elusive because the algae growth can obscure it by consuming it as it's generated and the algae proliferates. It's a guess but I think this may be it.