magnesium
 

Hey all, have a concern, my magnesium was 2400 3 days ago, i did a water change only 3.5 gal in 40 gal tank and now my magnesium is reading 950. why the huge drop and what can i do to stablize? also my phosphates were at .08 which i know is too high and after waterchange is reading .11.

misread the first reading?

2400 seems awfully high. I agree with Mark that this sounds possibly a bad test reading. I can't even get a reading that high on my Mg test kit unless I refill my titration syringe.

950 sounds believable. (Low, but believable.) Depending on salt mix, Magnesium readings vary quite a bit and some have low Magnesium. You should test your freshly made water change water so you know what Mg value you're working with. I have to add a fair bit of Mg to my water change water otherwise I pull the Mg down with every water change. You want to aim for around 1500-1600.

If that PO4 reading ppm? If so that's not too bad a reading. PO4 readings vary hugely from day to day and even time of day. If I take a PO4 reading half an hour after I feed the tank I can expect it to read anywhere from 8 to 20 ppb and if I take a reading in the morning 12 hours later I get a legit 0 reading (I use a Hanna handheld).

so if i wait til tomorrow morning a take another reading may be more acurate?

Do you mean for the Mg or the PO4? If PO4, sure, probably; if Mg, it probably doesn't matter morning or night, but if you get a reading like 2400 again, maybe do a second test right away.

Where the SG's the same between the 950 and 2400 readings on the magnesium?

Tony, you keep magnesium at 1500-1600 ppm?

I agree with Tony, sounds like a goofed up testing. It won't swing from 2400 to 900.

Sorta.. realistically I'm happy with anything above 1400.

I've never kept mine over 1400 ppm. What benefit do you see? You use Mag chloride or a mix with Mag sulphate?

I use a mix. Anemones looks better with the Mg at those levels (don't ask me why they care, but they do - I can always tell when my Mg has gotten too low by looking at the anemones), plus, although it could be hearsay I keep hearing that higher Mg levels help keep hair algae and bryopsis at bay.

ok u guys have got my head spinning, i only just started this most favorite hobby I have ever had in my life and already I am confused. I just need to know what to do to make my water good and btw I am building a sump with a refugium. newyorksteelo is my hero!

Ok, sorry :lol:

I wouldn't worry about Magnesium too much if you're just starting up. Just have fun with the hobby in the meantime. Honestly I went maybe close to 5 or 6 years into the hobby without once caring about Magnesium. :)

Don't worry, in some ways, the confusion will go away, and in other ways, it never does! That's why we're all off our rockers. :lol:

water test
 

so I did another test today and you were probably right about 2400 being wrong read, today my reads are cal 460 alk 12/ mag 1150/ phos .11/ how do i bring my phos down? all else seems to be leveling out, I think with one more water change I should have it pretty much under control (I hope)