Calcium carbonate precipitation can't reach optimum calcium and alk levels

[AnnaCassandra]

What could be preventing calcium and alkalinity from staying in solution and causing precipitation? It seems that no matter what I do my calcium settles around 380 and my alk stays around 6.7 to 7, I just measured mag at 1280. I started using kalk in my ato but it really hasn't helped, I tried to get my alk and calcium levels up to somewhere over 8dkh and 400 ppm with 2-part but they just won't get there and stay there, nothing in my tank is growing and I don't have enough coral for it to be a consumption issue. I've been battling a cyano issue that's aggravated by large water changes so I've been avoiding water changes until I get that under control (the situation on that front is improving) and the calcium and alk issues and lack of growth was an issue before the cyano started.

 

[bertoni]

How often are you dosing? My soft coral tanks consumed 2-3 dKH per day, just due to coralline growth. They required daily supplementation, and a fair amount of it.

 

[AnnaCassandra]

I really only have like 5 frags that are still alive and coralline algae hasn't really been growing well for a while, it used to grow on the glass if I hadn't cleaned it in a while but not anymore, we moved about 6 months ago and that's when everything started to go downhill we have well water at the new house but use RO/DI for the fish tank. We never used to have any calcium carbonate precipitation on the heater or in the sump and now it's everywhere, I really don't think it's consumption it's definitely precipitation there might be some consumption but based on the state of my tank I'm doubtful it's the major cause of the drop in levels

 

[Vinny Kreyling]

Anna, with well water you need to de-gas the water BEFORE it goes into the DI or you will deplete it REAL FAST. Possible cause of the problems ?? Perhaps Jonathan will reply again.

 

[outssider]

dose your alkalinity with sodium bicarbonate (backing soda) and not sodium carbonate (soda ash) or kalk......kalk and sodium carbonate temporarily increases ph which increases precipitation greatly!!!....also, add alkalinity slowly in an area with lots of water movement....

 

[bertoni]

Okay, if you are seeing buildup, then I agree the problem probably is (abiotic) precipitation. I agree with the baking soda suggestion. I'd try that for a few days, to see what happens, and I'd dose into the largest volume of water, generally the display tank. If the precipitation rate stays high, I'd get a second opinion on the test kits. They might be off.

 

[AnnaCassandra]

With regards to de-gassing the well water before it hits the di resin it's just not practical, I do go through DI resin fairly quickly like every 100 gallons or so but for a few dollars a month it's really not worth the hassle of trying to de-gas.

As I've been reading I've come across the suggestion to use baking soda instead of soda ash to increase alk, I'll try this and see how it goes.

I thought at one point a few months ago my test kits could be off so I actually tested the water when I bought some coral frags and the results were within range of what I would've expected,