Help with calcium

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Aquarium Advice Apprentice
Oct 30, 2011
Louisville KY
Calcium concerns!!

So in the last two months I've watched my calcium level fall like crazy. It's gone from 440 to now 280. My LFS said to do a 50% water change this week then a 50% next week. Then go back to my normal 10% the following week. So I did the 50 last week and checked today and it's still at 280ppm.
I was told that the reason my calcium level dropped so much was that the magnesium level was depleted in my tank. I do dose with B-Ionic daily. But two months ago was using purple up. So once again my LFS. Told me to increase the calcium dose by double, yet it has not helped. Any suggestions to what may be going on or how to raise my calcium. Thanks
Try dosing with kalk via your ATO it keeps your levels stable without spiking your ph and it replinishes your calcium slowly but constantly as evaporation from your tank is replenished with water dosed with kalk. I add 3 teaspoons of kalk to my 5 gallon container of water for my 76 gal. Just make sure to mix kalk by giving your container a good swirl as you fill it with water and let sit for a few hours before you use it for your ATO. Make sure your hose line of your ATO does not sit at the bottom of the container where the the undissolved powder settles. only the saturated solution of calcium hydroxide that sits right above this undissolved powder is what is beneficial to your tank .
What brand salt are you using? If you did a 50% water change and your calcium level didn't increase, I would say you have a bad calcium test kit.
What is your alk and mag levels at?
What brand test kits are you using?
Instant ocean and alkalinity at 160ppm. Not sure about mag cause I don't have a test for that.
I agree that the kit may be bad, have you had your LFS confirm the Ca, Mg & Alk levels?

Kalk is great in ATO, keeps my Ca at 500 or so. Stabilizes alkalinity & even precipitates out Phosphates. The only downside I noticed was that my Mg levels dropped quite a bit, so now I'm dosing Mg as well.
I bought a new test kit and it said the same thing. I also had it tested at my LFS and there's said 290.
Neither do I, I use a gravity drip system.

I measured the daily evap & did some math to figure out the drip rate. It's not an exact science, but works for now.
It takes some patience, tuning & caution, but its been working well. Keeps Ca & alk up all the time, along with SG and keeps water level constant for my skimmer. Cost about 10$ for airline tubing, valve & 2 gallon drip container.
How many hard corals do you have in your tank? Maybe think about getting a calcium reactor? Also where is your alkalinity levels? I know that can affect calcium.
Get a mg test kit. Once mg is depleted it takes tons to bring it back up. I used two bottles of kent tech m and I still dose daily
My LFS told me that doing the water changes would bring the mg back up and also replace all the trace elements that's lost. But hasnt helped so far. I'll get a test kit and test for mg.
Your alk is pretty much perfect. 160ppm = 8.96 dKH.
I still question the calcium test result. Using Instant Ocean you should see calcium around 400.
Mix up a batch of fresh saltwater and test it. You should see around 400 calcium, 196 ppm (11 dKH) alk and 1350 mag.
What's your salinity(SG)?

I highly recommend the new Hanna electronic test kits. They cost around $50 each, but they give you a digital readout of your parameters. No guessing what the color is.
Hanna Checker - Test Kits - PRODUCTS - English
I have the hanna phosphate checker and couldnt live without it. lol I plan on getting the calcium and alkalinity ones very soon.
Alright so I checked my saltwater makeup. SG was 1.025. And calcium was 410 on my test. I did a 50% water change earlier today and I checked my aquarium water also
SG 1.026
Ph 8.3
Nitrate 0
Nitrite 0
Ammonia 0
Calcium 300
Alkalinity 160
I don't know how your calcium can be that low after a 50% water change. It's a matter of simple math. Your tank water would have had to been at 200 ppm calcium. 200 (50% of old water) + 400 (50% new water added) = 600 ppm ÷ 2 (for average reading) = 300 ppm.
Anyway, if it's really 300, go to your LFS and look for Kent Turbo Calcium. It's calcium chloride pellets. Use that to raise your calcium up to around 400 and then regular water changes should keep it in that range.
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