You should usually test 6 hrs after dosing... Ideally 12 hrs as it will stabilize.

I dosed alk before and tested 1 hr after a larger dose. It skewed the test as it was sitting at 10dkh from 7 originally, tested 24 hrs later and it was at 7.5....

Conclusion, It is best to test the next day after dosing.

A cheap easy alternative is
50lb bag of Easy Start brand icemelter for your driveway $40
4kg jug of Epsom Salts $5
Mix it 11-1
I use 1/2cup per 5gallons of freshwater in my top up resevoir.
Been using this for a couple of years now. You can't really argue that it's unsafe for reef tanks as I learned this from whatcaneydo and well, look at pics of his tank:biggrin:

Well, I used up my 600 g Mg from Seachem, and managed to raise it from 1260 to 1350. Didn't seem to make any difference to my alk or Ca consumption and parameters, and my corals were not at all affected.

So will leave it for now, and see where it goes from her.

Well, my Mg didn't stay up for very long, back down to 1260 now. So I think I am going to have to get serious about dosing.

Where do you buy this Easy Start ice melter? And where is a good place to get a 4 kg jug of Epsom salts?

I don't use a top off reservoir. After mixing the Easy Start and Epsom Salts (11:1), can I add that mixture (after figuring out the appropriate amount) to my Ca dosing? Or do I need to set up a 3rd dosing pump? And what time of day is it best to dose Mg? Currently I dose Ca during the day and Alk at night.

I picked up mine from Amco. The epsom salts from Shoppers Drug Mart. I add a half a cup of the mixture to 5G of freshwater for my reservoir. Stays consistant at 1350. Whatcaneyedo is the dude that got me on to this. I'm pretty sure he adds a cup of the mixture to his water change but dont quote me on that. Shoot him a PM he's pretty helpful. Good luck bro

Thanks. Don't think we have an Amco wholesale in the lower mainland. Anybody know where I can get the Easy Start here?

Every time I read these threads, I'm almost tempted to measure my Mg :)

Are you suggesting I should hold off? I sure would like to.

What gets me is my Mg was running at 1260 before I raised it to 1350, and then a month+ later it is back to 1260??

And I should add that my Ca and Alk have been stable all along with my dosing. Maybe I should leave the Mg alone?

No, suggesting I should get off my lazy ass and test my Mg :)

I've overdosed my Mg before and played around with it alot trying to combat bryopsis. I've also brought it up by way over 100ppm in a day. It's really not a big deal as if you were dosing Ca. Worrying just makes you lose sleep. Unrelated to you but on side note, I might add that this wont work on bryopsis thats just the Kent stuff.