Hi and thanks for your suggestions. I appreciate the input.
I do agree with you about continuing to use Kalk in my ATO. I see no reason to replace it. I have been supplementing that by dosing a Sodium Carbonate (Soda Ash) solution using a dosing pump. I dose it evenly over 24 hours each day to mitigate any pH spikes.
I have a Kalk stirrer of sorts... Well not really but I have a 55 gallon ATO reservoir of RODI with Kalk. I periodically turn on a power head in bottom of the container to mix it up and max out the concentration. I shut off the dosing pump and leave it off until the solution settles out again. I try to keep it fully concentrated with a little extra Kalk on the bottom.
ALK is so important and I have been chasing it on this system for quite a while. At first I was fooled by a faulty reagent mix for my Hanna checker and spent about 2 weeks going crazy tying to figure out what was wrong with my system until I read about the issue they were having with their reagents going bad. I bought a new bottle and everything was fine until the same thing happened with that bottle as well. The newer reagent bottles do not have the foil top and they seem to be fine (so far). I also use other ALK test kits now to give me some peace of mind.
But I will get there and figure out how much to dose to keep things in harmony. Then I plan to add a lot more corals so it will be a gradual process to increase ALK to match the need.
Thanks again!!
Getting Alkalinity balanced can be really tricky prior to having any real demand from corals. Once you have things growing it will be more consistent an easier to track.
In regarding to measuring, I honestly decided to go back to the regular Salifert test in lieu of the Hanna. The regent for Hanna was getting expensive and the Salifert test is pretty quick! Plus Salifert comes with a standard you can check against.
One word of concern regarding your current setup for ATO and kalk mixing. Be very careful that your ATO never pulls kalk slurry into your aquarium. Install safe guards so this can never accidentally happen. It will nuke your corals and you will be sad. This happened to me in my QT tank. I was added kalk not thinking my Tunze ATO pump was sitting on the bottom of my reservoir. The next day the water was totally white because the ATO pump (covered in kalk sediment) pulled in kalk sediment and lost several corals.