New to dosing, here is whats going on.....

[dynomight]

So I started testing and dosing four days ago. I am using red sea test kits and feel that I have gotten good enough to minimize human error as much as possible. My magnesium is testing consistently 1400ppm. Calcium had originally tested at 450ppm but maybe due to some error because it has been consistently at 430 to 440ppm since.

I guess the real question is about my dkh. It started four days ago at 9.8. I waited til the next day and it was 8.8. Since I am shooting for 9.0 I dosed 5ml of my liquid additive and it retested at 9.2. Close enough. Then the next day it tested at 8.8 (just a note here, I test at the same time every day. Two hours before lights out.) So I dosed 5ml and it retested at 9.0. Hooray. Today it tested at 8.4. I dosed 10ml and it didn't budge. Another 10ml and still at 8.4. This is a tank with 120g volume including sump.

Sorry this is so long. I have done some reading but nothing caught my eye. Seems weird to me that calcium and magnesium are steady but not kh. I knew calcium would not be used up fast because it's a lightly stocked lps tank with a few softies. I'm also not sure of the ph but I do run my skimmer off outside air.

Sorry if I missed anything. Thanks in advance for any help.

[Randy Holmes-Farley]

Seems weird to me that calcium and magnesium are steady but not kh.

That's normal. Magnesium changes very, very slowly. Maybe 0.1 to 1 ppm per day which you'd never notice in less than a few weeks.

Calcium will only change by about 18-20 ppm for each 2.8 dKH change in alkalinity. So if alk drops by 1 dKH, you are unlikely to be able to detect the drop with a normal test kit. Water changes can also push it up since many have high calcium.

I'd just keep monitoring it twice a week to get a feel for what is happening to it, unless you choose to use a two part system, in which case you can measure calcium rather infrequently.

What are you dosing now?

[dynomight]

I'm dosing seachem reef carbonate and brightwell's calcion. These were the only two sold where I am and I didn't want to commit to much in case dosing didn't pan out.

I do 10% water changes pretty much every week with red sea coral pro. So I guess I'm not going to have a problem with dosing mag because this salt tests high. My tank also does not consume calcium very fast at all because of what I stock. But my understanding is that ca and kh are used in a fairly balanced equation. But I'm only dosing carbonate right now to even out the daily swing. Is that going to be harmful or throw off the balance between ca/kh? Or can I dose carbonate daily and keep an eye on calcium?

[Randy Holmes-Farley]

But I'm only dosing carbonate right now to even out the daily swing.

Daily swing in alkalinity? Not sure what you mean.

If the magnesium is high, then there no reason to bother measuring it or dosing it. :)

[dynomight]

I guess swing is the wrong word. The daily drop in kh. Seems to be about .5 daily.

[bertoni]

0.5 dKH is a very small consumption rate. It corresponds to about a 2-3 ppm drop in calcium, and far less than that for magnesium.