Cyno Bacteria Or Diatoms?

[Don Trinko]

I have 2 sw tanks (20 and 75) both are 3 months old. Both use the same salt mix and ro water. The 20 got some red/maroon on the sand but it disapeared. The 75 has it and even after I remove it it comes back.
Several have suggested that I do not have enough flow in that area (middle of the tank) so I added a 160 gph power head pointing to that area. ( total flow is 350,300,300,100,160= 1210, 1 filter ,4 power heads). Others have suggested to much nutrition in the water. My nitrates are 5.
The tank has 5 green cromis, 3 pj cardinals, 1 firefish, 1 royal gramma, 2 clowns, 2 pepermint shrimp, 2 cames shrimp, 1 turbo snail , 3 dwarf hermit crabs and 8 sand stiring snails.
Any Ideas? Thanks; Don T.

 

[xxBarneyxx]

Sounds like cyano. Does it form quite a thick mat if yuo leave it and feel slimy to the touch?

Lack of flow can cause it as can excess nitrates and phosphates. I have a bad case of it in my tank despite having no detectable phophate and extremly low nitrate (barely registering on test kit). I tried cutting down my lighting from 10 hours to 8 hours which I thought was helping for awhile but now its come back.

Cant offer a solution im afraid other then getting nitrate/phosphate as low as possible and increasing water flow (maybe cutting your light cycle down a bit as well). If you find a good solution let me know coz its bugging the hell of of me

 

[Don Trinko]

Yes , I think it's cyno. I only have 1 standard tank light and my nitrates are low. (5) I have the 160gph powerhead pointing in that direction. I will get a bigger power head. I don't have a phosphate test kit. I will get one but I use ro water to mix so if I have phosphates it is in the salt mix. Thanks; Don T.

 

[kj23502]

Don't rule out faulty or old membranes in your R/O unit so quickly. Have you tested r/o water w/a TDS meter? There've been a few times where I've read that was to blame.

 

[Don Trinko]

Yes; I tested my ro. It abought 12 TDS. I have a phosphate test kit on order and a bigger power head.
Thanks for all the ideas; Don T.

 

[kj23502]

Whats the TDS of the water before it goes throught the R/O unit?

 

[rabbut]

Eather liquid chalk is comming out of your tap, or the membrane needs some attention there IMO. TDS should be in single figues, idealy arround 4-5 as a maximum, though the hardness of your source water has some bearing on this...

Does your unit have a flush kit?

All the best
Rabbut