Cloudy tank and low pH

[mchammer]

I have a 8 month old tank and I've had the worst time trying to keep my water parameters stable. I've had a reef tank for 7 years before this one and I never had this much trouble. The tank is a 120 gallon and 40 gallon sump. I have a light bio load and I used dry rock and sand when I started this tank. My last water reading was July first just before I changed the water and the results were as follows: SG-1.025 Phosphate-0.00 (Hanna checker) ALK-9.74 (Hanna Checker) Calcium-380 (Sailfert) Mag-1200 (Sailfert). I know the Mag is low and after the water change I added 500ml of Magnesium Chloride. According to BRS calculator I should have added 1451ml but I didn't want to add too much at once. My pH has been trending lower for the past week or so and I'm not sure why. below is a copy of my pH reading from my Apex controller. 237334 you can see the lows at night are getting lower each day. I had to cut back on my ALK dosing because my previous reading was 11.424 and I know increasing ALK will raise pH. Today I woke up and found my tank looking cloudy. I haven't seen it like that since the cycling days. Could some one help me out with some solutions or reasons for the cloudy water and low pH.

Sorry for the long post but I wanted to give as much information as possible.

Thank you

[mchammer]

I just looked at this post and I noticed you can not see the graph that well. The high on the pH is 8.13 and the low is 7.87.

[bertoni]

dKH at 11.74 is a bit high, but not all that bad. I can't read the pH levels on the bit map, so I don't know what the pH levels are, but anything above 7.8 or so should be fine. The cause of low pH always is a high carbon dioxide level in the water, assuming the dKH is okay and there's no massive die-off causing a lot of decay.

The magnesium level is high enough for the moment. 1275 ppm is the canonical ocean average.

I'm not

[mchammer]

Thanks bertoni. I posted the range of the pH above. Is there anything I can do about the cloudy water. The last time I had this problem was when the tank was cycling. I assume it is a bacterial bloom or could it be due to the high ALK.

[bertoni]

You're welcome.

The alkalinity isn't high enough that I'd expect a problem. For pH, anything above 7.8 is fine. I suspect you're seeing a bacterial bloom. Some moderate, say 15%, water changes might help clear it up a bit more quickly. A UV unit could kill it fairly quickly. Personally, I'd stop feeding for a day or two, to try to starve the bacteria, if that's what it is.

[mchammer]

I'll stop feeding for a day or so. I have been feed a lot more because my tank is low nutrient and I was worried about starving my clean up crew. l lost a bunch of snails and a emerald crab recently and I felt that might be the reason.

[bertoni]

It's hard to know what's feeding the bacteria, but die-offs can do that.