Bubbles at the bottom

[EQCM2B]

First thing in the morning all is well in the tank, but as the day goes on and the tank warms up due to the MH lighting, (from 79 -to 84), the tanks develops hundreds of bubbles on top of the substrate. Is this normal, god or bad? All water are as follows:

ammonia-0
nitrite-0
nitrate-5
ph-7.8-8.0
RODI water

All livestock seem to be doing well.

Thanks,
Steve

[davejnz]

It sounds like the beginning of a cyano outbreak.It is normal for the bubbles to develop in cyano during the photoperiod.I would increase your flow rate near the substrate as well as increase your PH slowly over the course of a week.Try to get it to 8.2(just before ligths come on)to 8.4(right before they shut off).The easiest way i've found to maintain high PH,calc,and alkalinity is to just use kalkwasser/limewater.
BTW,a 5 degree temp swing isn't a good thing IMO.You really need to think about getting fan/fans in your canopy to vent that heat from the MH off.1-4" fan per halide should do the trick

[JustDavidP]

What he said :) What you are seeing are gasses given off during photosynthesis. It could be cyano...but then again, it could be anything that 'respirates'. Reduce the photoperiod and move more water across your sand bed. Other than that, you may have to 'wait it out'. Almost all systems (newer ones) go through a phase that looks like this:

Set up --> Diatoms --> cyano (sometimes) --> stability.

Dave

[rickm]

I've had this on my sand and also on my LR.No evidence of cyano. Others have asked this question on other boards. Some say it's algae converting CO2 to O2 during the day. Others have said it's gases from bacteria working within the sand bed. I don't worry much about it as it doesn't seem to be an issue.My ALK is between 13 to 15 dKH and CA around 450 ppm with Kalkwasser dripped in every nite. I run my fuge light counter to my tank lights and PH drifts from 8.1 to 8.3.