DkH

[Snappy]

sphelps8 to 9 I think on average is best. If you start going over 10 you'll get alk burns on some of the sps corals. I have read however that some salts have higher levels of metals such as boron which actually gives a false Alk reading on test kits and if you're using such salt you need to maintain higher Alk levels around 11-12 to achieve actual alk levels of 8-9. Not sure on all salts but I know Ocean Pure is one of them. I believe the "best" alk level will depend on the salt you use and the types of equipment you employ, a little experimenting is necessary to determine what is best for your system.

I also seem to recall that natural seawater usually doesn't exceed 8 dkh.

I agree unless you run a ULNS like zeovit for example, then it is recommended your DKH is a bit lower. My experience with Ocean Pure salt wasn't great so I don't recommend it for an SPS tank.

[whatcaneyedo]

I didnt experiance an alkalinity burn on an acropora until my alkalinity shot up to +20dkh due to having too much flow through a calcium reactor. The flesh just pealed off the acro almost instantly. I havent lost anything like that while keeping my alkalinity in the 11dkh range.

[fencer]

Hmm..comments are interesting. The DkH of sea water is 7.5. Because I run Ultralith I have to keep it around that mark. I have tried raisng my DkH even 1 point I found I was tossing in a lot of Carbonate. I find it hard to even consider a Dkh of 9 as trying to raise it that high would probably throw my other prams out of wack. For those who have consistently high DkH I wonder if it isn't the salt that is doing it or not using RO/Dionized water for make up.