Kalk precipitation or something else

FishyFishFish · Apr 29, 2021

I have a fairly new tank (2 and a half months old) and recently started dosing Kalk to bring the Alk up to a target of 8.5 Dkh.

I tested the Alk over a period of a few weeks and determined that I would need about 50ml of Kalk solution per day to keep it stable. As I am new to this, I started very low (4ml per day) and have slowly been increasing it; I am currently at 24ml per day. Whilst I have been raising the Kalk dosage to achieve my target Alkalinity, I have been adding baking soda to keep it stable.

My water has lots of white particles in it. There is some 'powder' looking stuff on the back of the frag racks and some of the rock work (near where they were glued together) are looking very bright white. The water surface has lots of particles on it. The only mechanical filtration I have is the filter floss at the top of the Evo filter chamber.

I am currently dosing at the slowest setting I have available, which is 4ml/min. This runs for 15 seconds (1ml) every hour and the outlet drops the Kalk solution just in front of the return pump outlet. The Kalk is the dosing container is clear where the pickup tube is.

Is this likely to be a precipitation problem or could it be something else (e.g. the salt, which is IO standard)? I have also been adding Reef Chili and have some pods in there, but it does look like undissolved powder.

I have been testing the water a couple of times a week and it isn't showing anything out of the ordinary, so I have only conducted 2 water changes (one 10% and one 20%) in the 2 and a half months the tank has been running - do I need to up my water changes?

How do I determine what this is and how to clean my water?

mdrieder · Apr 29, 2021

Turn of the doser for a day or more and dose by hand in a flow area ensuring no precipitate. (it happens almost instantly if its gonna happen) and see if that helps the problem. Salt doesn't dissociate in water once properly mixed so we can rule that one out. Also some pics would really help.

blasterman · Apr 29, 2021

Kalk precipitate forms on pumps, heaters etc as white gritty powder.

Poorly mixed kalk looks like white pepper, but it dissolves fast and it sinks.

What you are describing doesn't sound like kalk.

Randy Holmes-Farley · Apr 30, 2021

Something doesn't add up here. The calculation seems off unless this is a super small tank.

What size tank are we talking about?

50 mL of saturated limewater (kalkwasser) will only raise a 10 gallon aquarium by 0.15 dKH.

That's not enough to cause a problem, or be very useful in typical size tanks.

FishyFishFish · Apr 30, 2021

Yes, it is a small tank. It’s a a Fluval Evo 13 gallon. It’s also fairly new.

I know I might be able to get away with just water changes but I had the Kalk and a doser here so I thought I might as well use it.

I’ll try some small water changes and increase the frequency of swapping out my filter floss, and see if that helps.

Thanks for the responses.

Randy Holmes-Farley · Apr 30, 2021

FishyFishFish said:
Yes, it is a small tank. It’s a a Fluval Evo 13 gallon. It’s also fairly new.

I know I might be able to get away with just water changes but I had the Kalk and a doser here so I thought I might as well use it.

I’ll try some small water changes and increase the frequency of swapping out my filter floss, and see if that helps.

Thanks for the responses.

Is the unit dosing clear liquid?

You sure it did not dose more than 50 mL in a day?

FishyFishFish · Apr 30, 2021

The dosing tube is attached to a fitting in the hood that drops the liquid right in front of the return pump outlet. When the dosing pump is running the liquid enters the water in drops (not a stream). When each drop hits the water, it looks like a smoke ring, but it disperses immediately.

I don't watch the doser all the time but it seems to be running correctly. It is a GHL 2.1SA so hopefully fairly reliable and consistent. The amount of fluid in the dosing container suggests that it isn't wildly out (it is a 48 oz bottle and has used less the half of the mix over 18 days). The solution was mixed at 1/2 tspn per 32 oz.

The baking soda mix that I am using is a crystal clear solution. The Kalk solution does look very slightly milky.