In past years, before reactors, I always used ESV magnesium with good success. When I started to run a reactor with ARM media, the level was always around 1350ppm.

I dont run a reactor anymore. I now add a magnesium product to any new batch of saltwater. Plus a spoon of calcium, to bring it up to proper levels.

The main tank is 180gal and I estimate the sump has 25gal in it. (EDIT: The sump tank size is 33gal, so instead of calling it 213gal gross I call it 205gal net. Ya, I know. Whatever. Sorry for any confusion this may have caused.) I realize that the LR and LS displaces water and that the 205gal isn't a true net amount, it's just that everyone, for the most part, when speaking of their tank's size refers to them as the size that they are....as if nothing were in it. Unless someone knows a formula for how much water LR/lb displaces I will continue to go with 205gal. There is also a density issue with the LR that complicates figuring that out. Your 95.2/170 works out to 56%...or, looking at it the other way, 44% of your system taken up by LR & LS, etc. I am quite certain that I have more water in my system than 56%.
Also, I need some sort of benchmark and I do not intend to dump all the Mg in at once and then test, but rather I will add and test in intervals. So, hence the 205gal as a benchmark...and yes I agree that I will probably have some left over, but it is not as expensive as some might believe, IMHO. Check out the price of a Kg at J&L. It is actually quite cheap, IMHO.

Cheers,:smile:

Yeah, it's crazy how much Mg I go through, in all three tanks! But I'm getting astounding coralline growth where I had little before, especially in my MH tank. Even my halimeda is prospering.

I go through periods where I pay close attention to the chemistry in my reefs and other periods where I test and adjust alk, Ca and Mg rather infrequently. When dripping kalk nightly, I really notice how low Mg gets and how Ca stays at about 400 ppm. When I don't drip kalk for periods of time, Ca and Mg get low. Alk is always low, whether I drip kalk or not, though it is much, much lower when I don't drip kalk nightly.

I wish the chemistry guy at RC would do a study on how much Mg and how much Ca is required to build stony corals, coralline algae and calciferous algae. We might be surprised with what he finds out.

Bev have you ever checked out your newly mixed salt water for Mg? That seems like a pile of it to go through. I run calcium reactors on my 2 large systems but not on my 44g, 24g or 12g and rarely do I have to suppliment mg. I was using formula salt which tested at about 1200 for mg but am switching to Tropic Marin and Seachem salt which I have not tested newly mixed up water yet.

Ruth,

Am using Kent salt, which I understand may be low in Mg. Haven't tested it, though, after mixing up a batch of NSW.

Also, don't have Ca reactors on any of my tanks. Heck, don't even skim or have sumps. Very low tech operations in our reefs. Rely on hands on work to keep our BB tanks in shape. Should take some pics of them and post to the new thread. They look great. No nuisance algae in any of the tanks. Corals, BTAs and frags are all doing very well :)

I just tested my Kent salt batch for Mg.

I mixed up about 18g @ 78F & 1.025. My Mg was right around 1220ppm. (Salifert) This I imagine would be alittle higher if I was mixing to 1.026

Thanks for sparing me doing the test :biggrin:

So it would appear that my systems utilize a lot of Mg.

I wonder how many people actually test and record Mg levels in their tanks and how much they dose to top up their levels when they test low???

I test for calcium, Alk/hardness and mg. every 2 weeks when I do water changes. If my mg. is a little low I dissolve a couple of heaping tablespoons in a glass of tank water and add it to my sump and then test again and repeat if necessary. All my test kits are Salifert and I replace them every 6 months whether they are used up or not. My 44g cube which has SPS, LPS and softies in it I think I have only had to add mg. once in the last 6 months.

Me, I include Mg in my bi-weekly tests and I correct it then and there if it is below 1350.

Steve

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Good thread! Anyone out there using Epsom salts for Mg supplimentation? It would be by far the cheepest way to do it. Also, I've had this lingering question for a while about ARM media. I don't have a Ca reactor, but would would the effects be of throwing ARM media in a filter bad in my sump?