Diatoms

[MickTheFin]

I just can't seem to get rid of what I assume is diatoms across my sand bed (Brown powdery stuff). No matter what I do, it just seems to come back after a few days.

I'm running anti-phos in a reactor and on a Salifert Phosphate kit, the test appears a little cloudy but there's no hint of blue at all. Using the Nitrate kit, from the top of the glass it appears closest to the 2ppm colour, whereas from the side most like the 50ppm. I'm guessing then that my nitrates are between 2 and 5ppm (50/10)...

I reckon these parameters are reasonably good, so why won't the diatoms go???


Should I get more CUC to turn the sand over more?

Alternatively, I only have a 3 stage RO unit with no DI polisher. Maybe Silicates are getting through the membrane? Should I get a DI pod to add to my RO unit before adding more CUC?

All advice greatfully received :)
Mike

[Tangman]

Hi is it a newish setup if so you do get these blooms from time to time. What lighting have you and how long is it on for. Also how much flow have you ie times turnover is there going through the tank. Finally what is your TDS reading of the RO water out of the RO unit as you need zero reading. HTH Twiggy:D:D

[moorish]

as stated in newish setups you get the diatoms,also reducing the lighting period can help.a deioniser pod would help and you would need to test the water coming out with a tds meter.derek

[MickTheFin]

Hi.

To answer your questions:

The tank was set up July/August time, so it's around 6 months old. Water movement is provided by 3 Seio 1500 pumps, so that's 18000 lph in a 600 liter tank or 30x turnover.

With regard to lighting, I have 2x250W Halides, 1x80W T5 Marine white and 1x80W T5 Actinic blue. The MH are on for 6 hours a day with the T5s on for 8 (Come on an hour before and go off an hour later).

My RO always reads 0 TDS. However, the TDS meter has an accuracy of +/- 2% FS, so in reality it could be upto 40ppm and still read 0... Is there anywhere that sells more accurate TDS meters?

Cheers,
Mike

[Tangman]

Hi that all sounds ok has it been there all the time or just come a few weeks ago. You could try some more CUC ask Macca he will put you right, have you tried syphoning it off. Twiggy:D:D

[gregh]

Is it "snot like".........and does it appear worse when the lights are on???

[MickTheFin]

No, it's not really like "snot" :D. If I was to describe it, I'd say it was like the cocoa power dusting on some confectionary. It's the same when the lights are off as when they are on.


When I first set the tank up I only had the MH lights. A few weeks ago I added the 2x 80W T5s and it seems to have appeared since then.

Thanks,
Mike

[Macca]

have you tested your silicate levels?

James

[MickTheFin]

Not yet, no. I'll pick up a test kit tomorrow.

Mike

[Tangman]

Hi why not do a little experiment and turn off the lights that you added and see if it goes , as a friend of mine put T5s onto replace his T8s and he got red slime algae all over the tank within hours. So it is maybe the other lights that are causing it. HTH Twiggy:D:D

[trik]

Hi mike, it may well not be diatoms, try turning your anti-phos reactor of for a couple of days, as you may well be over fluidizing it, Just a thought.

Richard