Water chemistry gurus: Cloudy tank; no precipitation?

[cr500_af]

Tonight I had done my normal evening check/feeding etc and all was well. A good friend called and I talked to him for about two hours. When I came back through the living room my tank was very cloudy... not a snowstorm/visible particles, but milky... milky enough that with only the moonlights on I couldn't see more than 4-6" into the tank. The fish that were out seemed to be fine with no visible stress.

NOTHING has been dosed in the last week. Literally nothing went into the tank besides food and RO water through the ATO. There have been no reactors (Ca, Kalk etc) running in weeks... I have my kalk reactor offline for repair.

Current parameters (the ones I checked) are:
SG 1.025
Temp 79.4 min/80.0 max in the last 24 hours
pH 7.9 (hours after lights out)
Ammonia 0
Nitrite 0
Nitrate very close to 0. It is 0.2 or less, the color is hard to distinguish (Seachem).
CA 475
Mag 1200

The only obviously out-of-whack parameter is alkalinity, which is somewhere between 1.5 and 2 Meq/L. My tank's normal alk level is 2.5-3.0.

I know that if your alk is off enough, it can cause Ca to do strange things like precipitate... which hasn't happened here as my Ca is fine.
Keep in mind that the tank went from clear to milk somewhere inside of two hours.

Just to be safe, I did a 15g water change as I always do if anything is strange in my tank. I also put my dual media reactor online, which was already set up with carbon, phosgard and filter floss last... just because I was concerned about toxins, etc in the water.

The water testing was done before the WC and reactor installation were done.

What tie is there between low alk and my symptoms?
I'll be the first to admit that I don't stay on top of my dosing as often as I should, but even with my habits (which sometimes mean I don't test or dose alk more than every couple of weeks) I have never seen my alk that low. With that in mind, it would suggest a comparatively quick drop in alk, though I fully understand that it by no means is a sure thing.

My temptation was to go ahead and dose some alkalinity, but I'm not confident enough to do so until I understand what is happening here.

Thank you in advance for any insight, guys!

 

[weaglereefer]

Possible bacterial bloom?

 

[ralph atl]

raise your alk! prob just calcium. (hopefully, anyway)

 

[lilrobb]

Calcium precipitation, check a powerhead any wide dust on it there?

 

[cr500_af]

Nothing precipitated at all. No dust, and the test numbers are from after the issue... the key point being that CA is still 475, and that is where it is kept. I've never had it above 500 before. If low alk > CA snow happened, my CA level would have dropped a lot as it fell out of the water column. I have dosed some alk this morning (which went fine, meaning everything appeared as usual when I dosed it, nothing weird).

This morning (which is only a few hours after my post) it is a little clearer, but not much.

Bacterial bloom crossed my mind, as did spawn, but who knows? No way to test for it of course. Can bacterial blooms happen in the course of an hour or two?

 

[grouper therapy]

Could anything have disturbed the sand bed enough ?

 

[cr500_af]

grouper therapy;565994 wrote: Could anything have disturbed the sand bed enough ?

I do have a melanaurus wrasse, but she's only gone sand diving once, when she was brand new and the YT was being a bully. No sand sifters in the tank at all.
I'd be happy if I just knew what else to test for...

 

[mojo]

Every time that I've seen this, it's due to calcium not being dissolved into the water column. Typically you see it when first setting up a tank and adding a bunch of salt into the RO water, but I've seen it happen before with a tank.

The typical cure is to add about 1/4 cup of vinegar at a time to lower the pH enough for the calcium to re-dissolve. However, in this case, with live corals, I wouldn't recommend that.

I'd give it a day or two an see what happens. Maybe do a couple water changes to be safe. If it's calcium, it won't hurt anything. If it's a bacteria bloom, you can't do much about it. If it's sand, it'll take care of itself. Either way, I think your hands are tied at the moment.

 

[cr500_af]

The conditions are probably 75% back to normal today. Calcium level is still steady as it has been, alk is up to 2.5 by dosing early this morning.

Chris, is it possible to be calcium with no precipitation at all? I have examined water samples as well as the rock and equipment itself, and there is not ANY matter that has settled out of the water column. A sample in a clear glass left all day has not resulted in any material settled out, and viewing it with bright light from the back it appears that there are no suspended solids at all... it's very much like water with a little milk added.

 

[mojo]

Yes- I've seen the cloudy effect without seeing any precipitate at all- it looks exactly as you've described. Unfortunately, I've never been curious enough to test the water to know what the pH, calcium, or Alk was when it happened- I've always just lowered the pH temporarily and moved on.

I still say to just wait it out.

 

[cr500_af]

Thanks Chris, that's exactly what I'm doing. In case you missed it above, the CA level has not changed at all... now, as to whether the improvement is due in part to raising the alk level, I couldn't say. However, I'm not complaining as long as it's getting better. All the livestock (including my RBTA, which normally gets really PO'd with any sudden parameter changes) have been just great, acting like nothing was wrong at all.

Also, just for sake of posting it, the pH which was 7.9 last night in the dark, is still exactly the same after four hours of lighting.

 

[mojo]

Yeah- I can't explain why your levels are otherwise normal - other than possibly the cloudiness happened (due to oversaturation of calcium or whatever) and THEN you're seeing the new levels. Dunno. All I can offer is my past experience.

If it goes away on it's own, then I'd chalk it up to calcium and not worry about it.