magnesium

[figdish]

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.

[mark]

misread the first reading?

[Delphinus]

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).

[figdish]

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

[Delphinus]

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?

[Myka]

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.

[Delphinus]

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

[Myka]

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

[Delphinus]

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.

[figdish]

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!