Magnesium Consunption

[skinsncanes]

I'm trying to figure out what is causing huge amounts of magnesium consumption on my tank.

I used to just do regular water changes, weekly 20 percent with reef crystals.

I have a 280 gallon tank with about 20-25 small sps frags. One giant (almost a foot when out and happy) plate coral and a decent size rainbow acro.

Half of the frags were added about a month ago, including the plate. Since I had such a large tank with so few corals before I wasn't dosing often just doing water changes.

I now test daily with a photometer to try and get my levels exact and stable and my dos is setup.

Originally my magnesium was ~1050. I just figured that's because I had never dosed magnesium and maybe the salt was low. I brought it to 1350 over a few days (which is gallons and gallons of BRS mix, gonna have to find a better way) but it still seems like I'm losing 50-100 PPM a day. I read on here people saying 4-8 PPM per day was high.

Any guesses? My photometer is new and should be very accurate. I test it once or twice a day so I'm seeing it going down and back up when I add.

Right now I'm dosing 300ML of soda ash throughout the day and only about 100ml calcium chloride. I was doing 200 of each but it raised my calcium to 500 and my dkh was 6.7. 7.5 and 420 are my targets.

Bare bottom tank. Tons of flow. I have hardly any algae. And really only a few rocks with coralline. Long story short I had a long battle with vermetid snails so 80 percent of the tank rocks are dry rock that I nuked and has only been in the tank two months. Can new rock absorb magnesium maybe?

I know this is a long post but I tried to provide most of the relevant information. I'd rather not have to dose a gallon or two of magnesium a day. I'm researching now buying bulk ice melt or some other cheaper option for dosing. I'll take recommendations from others that have high dose amounts.

I have 20 frags coming in a week so I will be continuing my daily or twice daily testing for a while since my consumption is going to change a lot again.

 

[skinsncanes]

Here since no one likes a post without pictures lol

 

[Pittsburgh]

What photometer are you using for Mg?

Otherwise, standard troubleshooting applies:
- test freshly mixed salt water at 1.026 salinity. Compare results to what's advertised for the salt mix.
- Double check your readings with another test kit, preferably a different and trusted brand
- Look for any precipitation, unlikely for Mg but still. Read on it more here: http://www.reefkeeping.com/issues/2005-07/rhf/#17

I'm not seeing much purple algae and those frags are still tiny. Can't see them taking up that my Mg or kH for that matter. 300ml of soda into an empty albeit huge tank is a lot of dosing... Screams precipitation to me...

 

[skinsncanes]

Seems like there's some precipitation in the sumo but bit the tank. I gotta read that article closer. It's the idip 570 photometer. I have a batch of salt mixing now that I'm going to test later today.

What makes it predicate?

 

[Pittsburgh]

Hmm... there was a looong discussion on the accuracy of this photometer wrt Mg testing. I don't know much, but from what I remember they don't directly test Mg, but instead it's a calculation from Ca and hardmess test results. I have no idea if those results should be trusted.

 

[MacPhisto]

Best way for you to raise Mg is by using Magnesium Sulphate (MgSo4). 25gr for 100L of tank water will raise your Mg by 25ppm.. only raise Mg 25ppm a day and wait a few days before testing, i don't know why but it always takes a few days to get stable. Just mix it in some tank water.

There is nothing in your tank that consumes Mg, but the actual ammount of Mg is only 12% or so so you need quite a lot of product to go from 1050 to 1350..
Make sure you buy a food grade Magnesium Sulphate.

 

[skinsncanes]

Maybe your comment about it taking a few days to stabilize is the issue. I guess we'll see. Doesn't change that it definitely seems like I need what I'm dosing to keep my ph in line and my dkh where it should be

 

[Piper27]

Don't chase pH, just alk. If alk is correct and stable pH will be good.
Is the tank fairly new? New tanks, even a new one tied into a running system will for some reason require magnesium additions for a while before it stays stable at a higher number. Maybe the rock is doing the same thing. I forget the reason this happens.
I would use a regular test kit from a good company to make sure your readings are accurate with that photometer.

 

[skinsncanes]

The tanks been going 18 months or so but as I said i got so frustrated w the vermetid snails that I took ALL my rock out. The back left corner rock has been in there the longest, about 6 months but the large majority is two months old.

I'm not chasing ph, I just know that when my ph is 7.7-80 all day that all is low. And when my alks good it's 8.0-8.3. I just monitor ph because my apex can't monitor alk, yet!

I flew through my two gallon containers or mag sulfate and mag chloride so I'll have to get more. Though I think I'll try Epsom salt and ice melt so save a ton of money. My magnesium was 1185 this morning, and 1050 this evening and I added a gallon of magnesium mix this morning. So something is happening with the rock and the magnesium

 

[ADVRESOURCE]

I dose 100ml MG daily. You will get MG drop with C-Algae growth. You can adjust PH by increasing surface flow using your power heads. The more flow the better CO2 exchange and the higher your PH.

MG usually effects salinity. Higher MG the higher salinity. (But, not that much). 1.026 vs 1.025.

I keep MG at around 1400 to 1440.

It's best to dose MG and worry more about ALK stability and CA.

Happy reefing!!

 

[skinsncanes]

All of my power heads are at the bottom of my tank not the top. I blast the bottom to keep detritus from settling.

Though I converted my wet dry sumo to utilize the tray for filter pads that I change daily. So alll the water drops a foot from the tray to the sumo water. Plus I have a large skimmer w outside air. And I have a sea swirl on my return to do the top surface of the water.

I'd say my coralline is minimal at best right now. I'll take my water to my LFS to double check the photometer but I still think something is happening w the magnesium. And from what people are saying my alk and calcium dosing is also high for small frags.

There's a big difference between you dosing 100ML, and me dosing a gallon!

 

[skinsncanes]

You ever get the feeling the tester knows you're talking about it....

This morning reading was 7.2dkh, 424 calcium and 1348 magnesium. All what my dosing is shooting for...

Though yesterday my calcium was high, 500. I found a few places that say high calcium could mess w magnesium.

Now that my calcium is spot on odds are my dosing isn't correct. I lowered it yesterday to fall from 500. Still 75 seems like a lot in one day for not a ton of big corals. I'll leave it for now and test later today and see. I'm looking for the number to drop and me need to slightly raise the dosing.

Though if my calcium really drops 75 a day the calculator calls for 2184 ml....so I'm going to hope and assume the tanks just not settled in yet.

Time to test the batch of fresh salt water

 

[robthorn]

Your tank is your tank. No two are alike. Nobody can tell you just by hearing a number that you are dosing too little or too much unless they are test numbers. Many dosing programs are designed to dose equal amounts but it rarely works out that way. You have to dose according to your test results and where you want to keep your levels.
It also depends how potent your additives are. Esv and Reefgrow raise your water different amounts per ml. On my 250 gallon I dose 115ml a day of magnesium. 120 of calcium and 238 ml of buffer.

 

[skinsncanes]

What do you guys get for instand ocean reef crystals?

I got 10.5 dkh, 504 ca and 1048 magnesium. Doesn't sound right...I did dkh and ca first and assumed I mixed it too stroking until the magnesium came in

 

[Pittsburgh]

I use regular instant ocean, but for reef crystals commonly reported numbers are 490/13/1440 at 35ppt

 

[skinsncanes]

13 dkh, why so high...i guess they target people that use sand and the waste eats up more alkalinity. I might have to change salts. I just mainly wanted the amino acids they add but I could get a separate supplement

 

[outssider]

I've been using RC for years and your mag is very low. should be in the 1300-1500 range. I once got a bad batch with low mag but this is rare. I would get a second opinion on your mag testing or use a quality kit to double check. mag consumption usually is approximately 11% of your calcium consumption.

 

[jda]

This is quite normal. You are not supplementing it and all true coral and hard algae will use it up. If you get a calcium reactor with natural media, it will get replenished along with the other major and minor trace elements. Three-part with mag chloride will also get this done.

BTW - you can add Muratic Acid to freshly mixed saltwater to bring the dKh down safely - it does not take much... search and figure out your volume. Just a few MLs might do. No need for new salt, just an adjustment.

 

[skinsncanes]

What's important is I've literally spent hours a day starring at my corals and I can without a doubt say they're all growing. I can tell you exactly what nubs/arms are new. Where they're expanded in rock. Where they regrew over glue. I know my kids very well