Try testing the pH at the end of lights on - at the end of lights out, the pH gets depressed because everything in your tank isn't photosynthesizing, it's respiring through the night adding more CO2 to the tank depressing the pH.

Also, I'd switch your Alk supplement to sodium bicarbonate right away and see if that makes the difference for you. I suspect it will.

Not if he's using the wrong supplement.

I've retested after the lights have been on for an 1.5 hours & it reads 8.1-8.2 based on color. If I do switch to the recipe 2 Alk supp how will that help with the ca levels? Is it through the slightly lower ph that ca is able to elevate because of the decreased alkalinity?

Last winter it seemed the ph was lower. Which is why I had chosen the recipe 1 for the slight raising effect. & it worked until august from march all paras were spot on. How does the system just change Like that?

ok so lets see if I got this right. at 4ml/gal you were causing percipitation and now your down to 1.67/gal and tyour finding you Ca is dropping.

seams pretty simple.. the number you want is between 1.67 and 4.

so try bump up your Ca additive a bit, say 2.0/gal reduce testing to every second day while you dial it in. once a week is how often a known stable tank can wait.

I personaly don't like the home made dosing as I find the consistancy of it isn't the best, but some people like it and have good luck.

Steve

Yes that's it! percipitation? How many people do you know doing much more than 1.5ml per gal? Correct. Do you mean increase testing to every 2 days? Home made dosing?

I will likely do this Thx.

Did you actually measure the new SW batch before adding?

Again as others said, dosing is to maintain what your tank consumes. After a WC supplement back up to your target levels and once you have matched your dosing to coral uptake, leave the dose settings alone.

Yes

just retested PH @ end of main lights out & it's at 8.4 so not much of a swing... maybe like .2-.3