DkH

[sphelps]

8 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.

[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.

[sphelps]

Originally Posted by 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.

Every tank is different, but have you tried a lower dkh? I rarely hear of anyone having good results at that level. What kind of salt do you use?

[whatcaneyedo]

Originally Posted by sphelps

Every tank is different, but have you tried a lower dkh? I rarely hear of anyone having good results at that level. What kind of salt do you use?

I have a problem with low pH. If I let my alkalinity fall to ~8dkh my pH falls to around 7.6 at which point my controller shuts off my calcium reactor and sounds an alarm. So I have to keep my alkalinity in the high acceptable range for the sake of my pH.

However, if it wasnt for my pH problem I would aim to keep my alkalinity in the ~8dkh range as it seems to be more natural based on what I've read.

I use both Seachem Reef Salt and Instant Ocean. 50/50

I agree with you, every tank is different. Thats sort of why I posted in this thread in the first place. The question of 'which DKH is best for growth' seems kind of silly to me because everyone will have their own reasons and experiences that make their preference different. But rather than flat out saying that I thought I'd just state my side and let the questioner figure it out on their own. Obviously a dkh of 8 for me wouldnt be very good if it meant my pH would be 7.6

[Aquattro]

I think it's safe to say that as long as you're in a range, you're fine. Same as Ca. Anywhere between 360 and 450 will be fine.
Alk between 7 and 11 is where I aim, and as long as you don't fall too low, you should get good results in coral growth.

[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.

[marie]

I like to run with a DKH of 9 just because I don't test very often and when my corals (and coralline algae) go through a growth spurt, alk and cal levels drop fast.
At 9 DKH I have a little bit of leeway before it drops disastrously low

[fencer]

Hi Marie
What do you think is causing this rapid growth in your tanks? That only thing that I can figure out that would drop your carbonate level that fast is clams.

[marie]

Originally Posted by fencer

Hi Marie
What do you think is causing this rapid growth in your tanks? That only thing that I can figure out that would drop your carbonate level that fast is clams.

Thanks to my regal angel I have no clams in this tank...coralline algae and corals are the only calcium suckers that I know about in there