Well hard to say. Source water could be at play to I think. But I have had 2 buckets and a bag both reading high 15-17dkh. It's tough to say.

Sorry. I have not measured alk in my mixes for over 6yrs now. I did have some with higher alk between 01 and 05 or around then sometime. Never had a problem with it any time since.

I did a 3g water change on my 20g sps tank yesterday with that 16 dkh mix and not a problem.

16?! Whaaat? We have not used IO in years, when we did we were seeing 10 and 13 with IO RC. What are you guys testing with? We use hanna and salifert.

Other salts we used/use

SeaChem Reef Salt 10 (we love this salt)
DD H2 ocean 10


Ray

IO is the reason I switched to seachem. Always had high KH with IO

That would be Salifert Ray. My mix included correct amount of magnesium added and a small calcium boost. Same mix I have been using for yrs. except for a brief try of Seachem Marine salt.

Ah cool, Salifert are very accurate..so yeah, that is a lot of ALK!

Well, most aquarists have to add an alk. supplement. I still use Seachems. So I would guess a slightly higher alk. in ones new salt mix would only assist that during a water change.

The only problem I have ever had was back 10yrs ago when had my 225g and on well water. Used an ro filter but not DI resin, which reduces the alkalinity in hard well water. It interacted with the salt mix and spiked my alk. Took me ages to figure out what the heck was going on.

DOH !!!.

Tap w/ prime and mine is sitting steady at 13 atm... I kinda figured it was a bit high, but thought I was just doing something wrong.

ninja edit: With IO

I made up a mix of IO I bought on boxing day, 16DKH. I've been trying to bring mine down, and had my calcium reactor off, test my water at 14ish, do a water change, the next day test at still 14. It was getting frustrating wondering how my tank wasn't bringing it down. Well, after this thread tested a new IO mix, now I know why. Thanks for posting, now I know why i have alk burn on a lot of SPS. My calcium is still high with the DKH, so it seems that the 2 are still balanced in the IO mix, just way too high.

Also, API test kit showed 7DKH the whole time. Took some water into OC and he tested higher, so bought a new salifert test kit that showed 14-16 in my tank. API test right beside it showed 7.

I have to stop "saving" money on my tank, it's getting expensive.

Glad that I posted the high Dkh too as I thought that maybe I was doing something wrong or thought maybe my filter wasn't working right. I am going to call Instant Ocean tomorrow and see what they say since so many people are having issues with the high alkalinity. I'll keep you posted.

Leanne