Check your calcium levels in your homemade 2-part!

[vapormd]

I posted this in the reef chemistry forums as well, but I've seen a few threads where others using homemade two part have had trouble maintaining balanced alk and calcium, so I figure I'd post in the general forum as well:

I've been using homemade two part additive following Randy's recipes and using bulk ingredients obtained from an online vendor. Since using the homemade two part, I've found that while I was easily able to maintain stable alk levels, my calcium levels would consistently drop over the course of a week to where I'd have to supplement extra calcium. After ruling out several different possible causes (abiotic precipitation, mixing errors, etc), I decided to check out the concentrations within my homemade solutions.

To make the calcium solution, I was using two level cups of calcium chloride pellets mixed with RODI water to make one gallon total.

To make the alkalinity solution, I was using two levels cups of sodium carbonate mixed with RODI water to make one gallon total.

According to Randy's article, the calcium portion should contain 37,000 ppm calcium. In order to perform testing using our standard calcium tests (I used Salifert, API, and seachem tests as a triple check), I performed a 1:100 dilution of the part 1 solution - which should read 370 ppm.

Sample 1 (fresh mixed): 260ppm
Sample 2 (two week old solution from a different batch): 230ppm
Sample 3 (another fresh mixed): 250ppm

The solutions I was using contained about 2/3rds the amount of calcium necessary to make up a balanced additive according to Randy's recipes, which probably led to my slowly declining calcium levels over time.

I've since started using three cups of calcium chloride pellets vs two cups, and have had no further problems with declining calcium levels. Another approach would be to increase the amount of Part 1 dosed, but that would kind of take away from the point of being able to dose equal amounts every day.

BTW - I performed similar testing on the alkalinity solution, which is supposed to contain 5300 dKH, and found my solutions to be pretty much on the mark. For the dKH I had to perform a 1:1000 dilution to bring the sample into the testing range of our kits, about 5.3dKH

HTHs!

[Randy Holmes-Farley]

I beleive there are concerns with the above discussion that are detailed here:

http://archive.reefcentral.com/forum...readid=1285556

In short, the recipe that is reported above is not the standard recipe.

[mille239]

If I may chime in real quick...The original poster did not mention whether he was using calcium chloride dihydrate, or calcium chloride anhydrous for the Part 1 recipe. I use the anhydrous, and according to the directions on the www.twopartsolution.com website, it does call for only 2 cups of the anhydrous pellets. The original poster did say he was using 'pellets' so I'm assuming he is using calcium chloride anhydrous as well.

[Randy Holmes-Farley]

Instead of bumping back and forth, I'll continue my part of the discussion, at least, in the other thread.