Alkalinity calcium question

maksim serebro · Jun 23, 2019

Hi all! Background: 7 months old lps tank. Started with dry rock and live sand. I do 15% weekly water changes. Over the last 2 months, my alkalinity has been dropping and my calcium has been rising. I’m using redsea and Hanna test kits and alk wants to stay around 7dkh and calcium at 470. I use reef crystals salt and only dose BRS alkalinity to increase alk. I have never dosed calcium in this tank. My question- is it normal for alk to decrease as calcium stays the same or increases and is it ok to just keep dosing alkalinity and not calcium to balance the numbers? Thanks. I’m a little confused on the issue. And , yes, I read Randy’s article on the topic and still a bit confused.

muzikalmatt · Jun 23, 2019

Following this thread as I have very similar issues with my tank. Nearly 6 month old IM 40g AIO, mixed reef doing 5 gallon water change changes weekly with reef crystals salt. Calc stays steady around 450 and alk keeps dipping below 7. I'm not dosing anything but starting to wonder if I should be.

Saintnovakai · Jun 23, 2019

Alk is more easily measureable than Calcium. You would most likely notice an Alk drop before a Cal drop on a test kit even if they are being used equally, which they are generally.

Auquanut · Jun 23, 2019

From my limited experience, you can dose Alk only to get it more in line with your calc. Once our parameters are more closely aligned, you may see a more noticeable drop in Calc. After 2 years, I'm still dosing slightly more Alk than Calc, but I have a lot of sps and inverts.

maksim serebro · Jun 23, 2019

Thanks guys! Still just dosing alkalinity until someone says otherwise. Just not sure why there is such an imbalance

Saintnovakai · Jun 23, 2019

maksim serebro said:
Thanks guys! Still just dosing alkalinity until someone says otherwise. Just not sure why there is such an imbalance

My best thought if advice is to check your test kit against another for Calcium. That should give you a firm answer.

Nicholas Dushynsky · Jun 23, 2019

What is your magnesium level as when that is where its ment to be it keeps the other 2 more stable I aim for 1290 to 1350 mag itkeeps my calcium at 440-450 and all at 7.7-8 but alk does seem to get used a little faster.

maksim serebro · Jun 23, 2019

Magnesium is at 1400 via redsea kit and calcium is checked with both Red Sea and Hanna checker.

Nicholas Dushynsky · Jun 23, 2019

That's good numbers then. Do you have coraline algae growing?

Randy Holmes-Farley · Jun 23, 2019

Reef Crystals starts with high calcium, even relative to its alkalinity, so ongoing water changes with it will help offset the calcium demand, and in a low demand situation, you may find that all you need is a small amount of alkalinity. Another source of calcium can be tAp water if you use that.

The magnesium level is not generally a cause for imbalanced alk and calcium demand. It raises or lowers the demand for both.

Rising nitrate can also deplete alk and not calcium, leading to imbalanced demand.

maksim serebro · Jun 23, 2019

Randy Holmes-Farley said:
Reef Crystals starts with high calcium, even relative to its alkalinity, so ongoing water changes with it will help offset the calcium demand, and in a low demand situation, you may find that all you need is a small amount of alkalinity. Another source of calcium can be tAp water if you use that.

The magnesium level is not generally a cause for imbalanced alk and calcium demand. It raises or lowers the demand for both.

Rising nitrate can also deplete alk and not calcium, leading to imbalanced demand.

Hi randy! Nitrates have been steady at 40 ppm. Maybe even higher 2 months ago. Is it ok for me to keep dosing just alkalinity?