What is it and what to do?

[hkgar]

Diatom, Dino or something else?
tank is 180 30 sump been up 2.5 years
I use RO/DI and it always test to 0 (two di filters)

I have an Algae turf scrubber
Flow return 700 gph, 2 Vortech mp40's at 65% (rc), 2 hydoer 1400's
Phosphate .01 Hanna Phosphorus checker
Nitrates 0
ALK 8.3 DKh
CA 450

pics

 

[Dkuhlmann]

Looks like dino's to me

You don't have near enough return pump You need something for that 180 over 2000 gph. You lose a lot of that from the pump to the head. I'm sure more will chime in on this to help.

 

[hkgar]

I am not sure I understand why a tank would need a 2000 gph return flow if the pump heads and the return are generating over 9000 GPH in the tank. (2 vortechs at 65% equals 5850 plus two hydors at 1500 is another 3000.

Also what does the pump size have to do with having dino

 

[Tang Salad]

I'll guess he was thinking that with such a slow turnover between sump and tank that your skimmer doesn't get enough tank water quickly enough to keep it clean. And that that's what is causing the problem. I don't agree with this, that's just my guess as to what he meant.

Anyway, the reddish color makes me think it might be cyanobacteria instead. Is it mainly in certain areas?

 

[Dkuhlmann]

Tang Salad Yes I'm thinking strictly tank turnover through the sump, nothing to do with tank circulation.