Sulphur reactor -> algae problem?

[Geddex]

I have a sulphur denitrator from Korallin.

The tank has been running for 4 years with very few waterchanges performed.

After less than 2 months in use it had removed all measureable nitrate. Very easy to set up and the only maintenance needed has been to let out the gas that is collected in the top of the reactor every now and then.

Instead of the nitrate problem I used to have I now have a problem with brown slime algae. It looks like I have too high level of silicates (not measured). Wether this could be a result of the nitrate reductor I dont know. ???
I would be thankful If someone could provde information about this.

I have not changed my RO unit for 3yrs. So the algae problem might have to do with this.

[Randy Holmes-Farley]

i would guess that the algae and the reactor are not directly related, but they may be.

Before you reduced the nitrate, did you have other algae (such as green algae) that were using nutritents like phosphate? Maybe you just shifted the conditions from optimal for one type of algae to whatever the brown slime is.

If the brown slime are diatoms, then perhaps the sulfur that you used had significant silica in it. That sounds unlikely to me, but possible.

[Mimbler1]

I would suspect that the brown slime is cyano, which can fix its own nitrogen from the water, and out-compete the better algae for phosphate,
Mike

[Geddex]

Thanks for your help!

I did have some green hair algae but not at all as dominant as the brown thing Im batteling now.

I noticed the high nitrate level by the "look" of the corals and thats why I decided to try a denitrator. (it was confirmed with a test wich I had not done for a long time)

I believe that the very quick reduction of nitrate level, and all the other reactions that it probably brought with it, put the tank out of balance.

[Randy Holmes-Farley]

I'd suction out the brown slime for a while and see if that alone does the trick.

Have you measured phosphate?

[Geddex]

Yes I have measured it and there didnt seem to be much phosphate. I could not notice any with my test kit.

I cleaned all the substrate yesterday (not a DSB!) but I can see the algae recovering slowly. Patience...!

[Randy Holmes-Farley]

OK. The algae may be using the phosphate rapidly and keeping it down.