What do you keep your ALK at and why?

[nuvocube]

Let’s hear it! Please include the types of corals you keep as well.


PFA

 

[Terry Le]

7.5 full blown sps. Suggested by Reef moonshiners

 

[Blitheran]

Acro dominated I use Kalk Reactor, still a young tank.

 

[allof fish]

Try to be high 7s or low 8s. Acro dominated sprinkled with LPs

 

[jackintheboxfish]

I try to keep my SPS tank 8-9. However ive always been curious about what would happen if I bump it much higher to 11-12 after encountering this paper

https://www.nature.com/articles/s41598-026-44817-6

The acros in the paper seem to increase in calcification rate linearly with alk increase while suffering no downside. (There did seem to be issue towards the end of the experiment but that happened to the control group as well so seems unrelated to alk increase)

 

[fish_collector]

SPS and clam only, 7-8 alk, I've found zero benefit in maintaining it higher.

 

[Ryan - Serious Reefs]

8-9 DKH is my goal and what I recommend to most people.

• 2-3 DKH away from danger in either direction. Protects against the inevitable overdose, empty jug, or unnoticed +/- change in consumption.
• I don't trust the test kits to be particularly accurate. Consistently close is what I am looking for.
• I don't trust most people to perform them accurately. Check out this video where we had 5 people perform various alkalinity test kits. The way people read them is wildly different.
• Providing a range rather than a number helps people understand they should trend back to the center rather than make knee jerk corrections.

 

[jackintheboxfish]

8-9 DKH is my goal and what I recommend to most people.

• 2-3 DKH away from danger in either direction. Protects against the inevitable overdose, empty jug, or unnoticed +/- change in consumption.
• I don't trust the test kits to be particularly accurate. Consistently close is what I am looking for.
• I don't trust most people to perform them accurately. Check out this video where we had 5 people perform various alkalinity test kits. The way people read them is wildly different.
• Providing a range rather than a number helps people understand they should trend back to the center rather than make knee jerk corrections.

Ryan your opinion is one of my top most respected ones.

An additional questions for you. Why do you think too high is a bad idea?

Also I remember in one of your SR videos you mentioned how in the olden days people will just dose a good amount of bicarb for the alk at once which I’ve heard is bad practice but nothing as to people experiencing negative effects.

Combine those two I thought maybe higher alk is a good idea in general as corals seem to care more about low alk and not high?

 

[Ryan - Serious Reefs]

I don’t know where “too high” becomes toxic, so I’ll leave that line to someone else.

What I do know is that I don’t like running 12 dKH or higher. The added carbon can drive photosynthesis and skeletal growth hard enough that you also need to think about the consequences, potential excess oxidants and rapid skeleton growth.

That might sound like a good thing, but if you’re going to push growth that hard, you’d better put just as much effort into gas exchange to help manage those oxidants and nutrition to grow enough tissue to keep up with the skeleton.

Rocket fuel only works if you consider all the angles. Otherwise, it just blows up. :)

 

[Ryan - Serious Reefs]

For what it’s worth, the current SR build series is largely about “rocket fueling” this tank to demonstrate some of these effects while still finding a responsible balance that most reefers can replicate. But it is important that all aspects are considered and not alkalinity in isolation.

In this case, I may push alkalinity as high as 10 dKH, but beyond that I’m not convinced the juice is worth the squeeze.

 

[jackintheboxfish]

Makes sense. Thanks Ryan! I’ll be sure to follow the series

 

[BryanM]

9, seems like an optimal balance for good growth.

Due to various errors I've had alk as high as 12, including starting with Redsea coral pro salt, or whatever they call it, that mixes exceptionally high.

 

[fryman]

I shoot for 9 but don't sweat too much if it swings +/- 1. I have a smaller tank that sits about 12 at the moment but seems fine.

I've been 7-12ish over the years in various tanks and it seems like so long as you don't change alk quickly anywhere in that range works.

 

[exnisstech]

8ish dkH on all tanks. It leaves me a cushion in either direction and coral grow fine. I'm not into pushing boundaries and I don't frag so no reason for me to chase accelerated growth.

 

[Bob Weigant]

Im between 8-9. Mostly chalices , some zoa's and some sps

 

[winxp_man]

8.5…. The system bounces 8.4-8.55.

Some of what I have.