Calcium precipitate = frozen pumps

[supersaltlick]

I have a JBJ 28g nanocube hqi that has been running for about 3years. I have several acro frags, 2 very large monti caps and several large LPS. I have been running Randy's recipe 1 for about 3 months and added kalkwasser about a month ago to decrease amount of 2 part dosing. I am dosing 35cc of 2 part per day and about 1gallon fully saturated kalkwasser via top off per day. I came home to both return pumps frozen today. Luckily I have a couple koralia nanos that kept water moving. I took out the return pumps and cleaned them in vinegar and now they are both running again. I ran these pumps for two years without cleaning them and cleaned them really well before starting my dosing program. Ca is at 440 and Alk is 9 (recently had to double dose for 2 days to raise from 7). I am dosing manually. Alk goes in half in AM before lights come on and half in PM after light go off. Ca dosed in 2-3 doses throughout the day when lights are on. 2 part is dosed into main display. Kalkwasser doses via ATO into rear chamber that one of the pumps occupy.

Is there a way to prevent this from happening in the future? Am I doing something wrong?

Thanks in advance for any insight on this issue.

Correction - kalkwasser is about 1 gallon per week. Not per day.

[bertoni]

How much Kalkwasser does the ATO pump deliver in a dose? Is it a stream of drops?

[supersaltlick]

Yes. ATO is done by aqualifter pump and it delivers a small stream. Not really drops.

[Randy Holmes-Farley]

Maybe you are raising the pH too high in front of those pumps.

Slower addition would help. Like slow drip. More mixing in the sump and higher flow through it will also help.

[tmz]

The Tom's aqualifter is pretty fast .22 liters per minute abut 3.5 gallons per hour per the manufacturer. Slowing down the ato so it takes at least 5 hours or five increments over the 24/7 ,if you ar not already doing so and changing the dosing point away from the pumps should help. Keep the dosing tube out of the water ,I'm guessing ou do that.

Maintaining magnesium around 1350 to 1400ppm can slow down precipitation too.

[supersaltlick]

ok. so it seems you guys think the kalk is causing the issue and not the 2 part. unfortunately the "sump" is just a couple of compartments in the back of an AIO system. So my solution may be to choke down the output via a needle valve and move it to the center compartment so the top off water can dilute out a bit before reaching the pumps. I may raise my mag from 1320 to 1400 also. Anything else you can think of to help? Maybe switch to recipe #2?
Thanks a lot for the input!!!

[Randy Holmes-Farley]

Well, it is caused by high (or locally high) pH and alkalinity, and to a lesser extent, calcium. Both can contribute. :)

[bertoni]

Recipe 2 will cause less precipitation.