Help Dosing Washing Soda --- Problems

[freddie40]

Randy,

I am having issues dosing washing soda. My 75 gallon tank is requiring 16oz of recipe 1 every day. A few weeks ago I was adding 8oz twice a day directly into my sump. Unfortunately, all of the walls in the sump and at least 1 in the tank were being coated by a hard white texture. I then started to drip the 16oz of washing soda every morining over 30 or so minutes directly in a high flow area in my tank. Unfortunately the same problem occurred, i.e. there was a white coating covering some of the glass in the tank, a very hard white coating.

I don't know what to do. Why is it happening? I switched to baking soda this morining, but my PH is now at 7.88 so that may not work.

How can I drip the washing soda and not have the coating problem?

Dave

BTW: I baked my Baking soda at 350 for 1 hour then added 2.5 cups to make 1 gallon. I know the temp was a bit high. Is this a problem? I also add the same amount of calcium made from Dow flake.

[bertoni]

The baking temperature was fine.

The white coating is likely calcium carbonate deposition. You might want to test magnesium. Low magnesium can allow more precipitation, although that's very rare in practice. A slower drip might help. What was the pH during the drip?

[freddie40]

My mag is about 1400. The PH during the drip yester was about 8.1

Dave

[bertoni]

Well, hmm, that's not very high. My only suggestion at this point would be a slower drip.

[freddie40]

I am only dripping the alk. Should I drip the CA too. Also, Should I drip at the same time or different.

Dave

[bertoni]

In this case, I'd dose them separately. I don't think dripping the calcium should be necessary if the supplements are dosed far enough apart, but I might be wrong.

[freddie40]

Right now I dump 16oz oz the CA as I drip the alk. I may buy another dripper tomorrow as they are cheap. I use a "Little Dripper"

Dave

[Randy Holmes-Farley]

Maybe try adding the alkalinity part to a higher flow area. You may also have an inaccurate measurement of alkalinity, pH, or magnesium. A slow addition of the alkalinity part to pH 8.1, magnesium 1400 ppm and normal alkalinity should not result in much if any precipitation of calcium carbonate.