Extremely low calcium & magnesium, yet everything looks good

[frisbee]

I've had my tank set up now for about 5 years. Other than dosing about 1 teaspoon of Seachem Reef Builder to every 5 gallons of top off water, (ATO) I've never really dosed anything. It's a 20 gallon mixed reef, & I usually do 2-5 gallon water changes each week. The corals look good, they've been with me for a long time, but as far as the sps/LPS corals go, growth has always been very slow. Anyways, I just bought a Salifert Magnesium & Calcium test kit. I checked both levels today, and my calcium was at 180, while the magnesium is at 810. The alk is at around 7 via a API test kit. Can something like this happen with these levels? I'm going to do a 5 gallon water change on Friday, and then re-test on Saturday, but these results just kind of threw me for a loop. Things aren't necessarily broke, but I guess growth could be better? Maybe I'm not using the test kits correctly? Any information would be great. TY.

 

[DaveK]

Those are extremely low readings. I'd expect trouble with your corals if they were actually that far out. First thing to do is retest. Before testing, make sure your SG is correct. If SG is off it will skew all other tests.

Next thing to test is your newly mixed SW to see if the issue is with the water change water. If both are that far out, verify that your test kits are good by having your LFS test the water or ordering a different brand of test kits. Usually it's best to order them from the large online stores, because they don't end up sitting on the LFS shelf for years.

Double check that your using the test kits correctly.

 

[BigAl07]

DaveK said exactly what I was thinking as I was reading the original post. Start off verifying your test results before you make any significant changes. Those numbers are VERY low and your coral would probably be showing significant signs of stress at those levels unless these levels were achieved over a VERY long period of time and even then I suspect the coral would look poor.

 

[sirrealism]

Agree with ^^^^^. The thing is I believe these results have happened over a long amount of time. If the results are correct then bring them back up very slow. They are used to having very low numbers and raising them to fast will shock them. raise them over the course of weeks not days. I did the same thing but it wasnt cal, it was mag 900 and alk 4.5, I raised them to fast and was on a roller coaster for a couple months. During that time I lost a couple nice corals so I will say this again if those numbers are correct then bring them up very slow.

 

[frisbee]

Ok cool. Thank you everybody.

I'm going to do a 5 gallon water change tomorrow, so I'll post the results. I'll have my LFS test the water maybe some time next week to double check. Thanks again.

Here's one of the more recent pictures btw. Things do look good.

 

[Danreef]

Why you want to repair what is not broken?

Do all the suggested to know where you are. BUT If you are happy with your tank and your corals are happy too with your husbandry...... why change ???

Cheres
Daniel

 

[frisbee]

Yeah, that's kind of what I'm thinking as well. Thank you.

 

[Choff]

Frisbee, I've had my tank running for just over 2 years and had a similar experience as you in that I never dosed, yet my corals had great color and everything looked healthy. Of course, nothing was growing or it was growing very slowly. I never tested my water much but levels were always ok and not quite as low as yours. I was religious with my WC and did 15 pct a week. Anyway, 2 months ago I started testing religiously and started up a calcium reactor. I have had more growth in the last 2 months than I have in the totality of the prior 2 years.

My suggestion is take a little piece from everyone above . I would consider starting to dose, but go very slowly. Just test your water for a few weeks and get an idea of your alk drop and ca consumption. Then start dosing and very very slowly being your numbers inline . Bulk reef supply has some great calculators to help you.

 

[Oxylebius]

I also ran my tank w/o dosing for 2 years (all sps), weekly water changes and numbers fluctuated weekly from corals taking in Alk & Ca. Just started to dose this summer b/c weekly water changes weren't cutting it any longer the numbers were getting way too low. I had good growth the first year and it slowed down the second year. Got to a point where the original corals were larger then my hand and added lots of frags where I had to start dosing.

Agree with above posts. Follow Choffs advice if you want to start dosing. You corals have slowly got used to the params in your tank. If you are looking to dose to get more growth, I'd spread raising the values over several months. But, first you need to see how much they are consuming on a daily basis and that means testing daily, and using the values right after a water change as the basis for each weeks consumption (test about a half hour after changing tank water). This will give you an idea of where to start dosing small amounts.

 

[frisbee]

Well, I tested my calcium & magnesium again. First off though, let me just say that these test kits were purchased a few weeks ago at Drs Foster & Smith. The expiration date on both is sometime in 2018. I'm also pretty sure that I am using these test kits correctly. (it's not rocket science) Anyways, I used Coralife salt, mixed 5 gallons of saltwater for 24 hours and then tested. Magnesium was at 1050, and the Calcium was at 430. I did a 5 gallon water change yesterday, and then tested the water of my DT today. Magnesium is at 860, while the calcium is at 225. Everything still looks good. (various montiporas, a couple acros, Lobo, acans, zoanthids, bubble, etc) This bag of Coralife salt that I'm using is almost gone, and I do have a couple 50 gallon bags of Reef Crystals laying around, so I'll use these next & see how it goes. I also have some Epsom salts on hand too, so if I do decide to start dosing, I can use the BRS calculator mentioned above and figure out what I need.
Thank you all for the information, & I'll try to keep you posted. Thanks again.

 

[Danreef]

Magnesium is low in your fresh mixed water. What about alk ? That parameter is very important.

I will move to Red Sea Pro salt or Reef Crystal. Those will have the correct Ca, Alk and Mag. levels when are fresh. If you change to one of those salts, I am sure that your standard weekly water changes will bring slowly the Ca/Alk/Mag parameters to normality. That will also provide time to your corals to adapt to the new conditions, because the full tank water change will take some month(s).

Well that is what I will be doing in my tank if my corals are driving well with those low parameters. Very slow change, as suggested by others.

Or will keep things as they are and enjoy the tank and worry if corals start to die.

Cheers
Daniel

 

[Oxylebius]

I checked both levels today, and my calcium was at 180, while the magnesium is at 810. The alk is at around 7 via a API test kit. Can something like this happen with these levels? I'm going to do a 5 gallon water change on Friday, and then re-test on Saturday, but these results just kind of threw me for a loop. Things aren't necessarily broke, but I guess growth could be better? Any information would be great. TY.

You know, it is widely believed that certain organisms calcify more quickly at alkalinity levels higher than those in normal seawater. This result has also been demonstrated in the scientific literature, which says that the uptake of bicarbonate can apparently become rate-limiting in the growth of some corals. For these reasons, alkalinity maintenance is a critical aspect in our tanks. In the absence of dosing, alkalinity will rapidly drop as corals use up much of what is in your tank's water. Most of us try to maintain alkalinity levels at or slightly above those of normal seawater. Those of us wanting the most rapid skeletal growth often push alkalinity to higher levels. That is why some salt formulas like red sea pro provide higher concentrations of Ca, Alk & Mg. It pushes the limit nearly to the point where precipitation occurs. And in doing so provides high amounts for accelerated growth. Therefore, with the lower levels that your tank has had it isn't surprising that you haven't seen much growth from your corals. But, they obviously had enough to survive, which is good for you!