Safe kh increase

[shaun1985]

so my corals looked pi**ed today so done my water change as normal for a Sunday and then tested and found my kh to be at 4.7
How much should I dose without upsetting the tank even more.
Thanks

 

[Scorpius]

Depends on what coral you have. I would raise it no more than 0.5 dkh per day, but that's just me.

 

[shaun1985]

I was thinking .5 per day too it seems safe as that is what it went up after the water change my fresh salt water reads 7.7 kh after doing a 5gal change it raised it .5

 

[Bob Weigant]

I also would .5 a day. Bring it up slowly

 

[Randy Holmes-Farley Verified Community Expert]

I'm skeptical that 4.7 dKH is real. Double sheck somehow.

But if it is, I think it might be better to rapidly bring it to at least 6 dKH. Alk that low is likely more stressful than a rise.

 

[shaun1985]

I'm skeptical that 4.7 dKH is real. Double sheck somehow.

But if it is, I think it might be better to rapidly bring it to at least 6 dKH. Alk that low is likely more stressful than a rise.

It was 4.2 to start with then did the water change and fetched it upto 4.7 it a true reading.
It’s ny fault tho had a lot on and never got around to dosing all week for some reason or another but didn’t realise how much the tank was using.

 

[Randy Holmes-Farley Verified Community Expert]

It was 4.2 to start with then did the water change and fetched it upto 4.7 it a true reading.
It’s ny fault tho had a lot on and never got around to dosing all week for some reason or another but didn’t realise how much the tank was using.

Unless you tested a standard, I'm not sure how you can now it is a true reading. MANY of the unusual reports here end up being test error. It is very common to get a false reading, and VERY uncommon for alk to get that low, even if stopping dosing.

Depending on your pH, rock and sand would begin to slowly dissolve if the pH got even to 7.8.

 

[shaun1985]

Unless you tested a standard, I'm not sure how you can now it is a true reading. MANY of the unusual reports here end up being test error. It is very common to get a false reading, and VERY uncommon for alk to get that low, even if stopping dosing.

Depending on your pH, rock and sand would begin to slowly dissolve if the pH got even to 7.8.

Excuse my ignorance but I’m guessing by what your saying is that ph would be affected by my low kh ? Thank you for your quick response I’m struggling to see how it can have dropped so low so quick too

 

[Randy Holmes-Farley Verified Community Expert]

Excuse my ignorance but I’m guessing by what your saying is that ph would be affected by my low kh ? Thank you for your quick response I’m struggling to see how it can have dropped so low so quick too

pH will naturally be low at that alkalinity, but my main point is that while pH 7.8 is normally fine for a reef tank with normal alk, at pH 7.8 and an alk of 4 dKH, aragonite is close to or actually undersaturated in seawater, so rocks, sand, and coral skeletons may slowly dissolve.

That alk is also very stressful for corals, and I'm not sure they can take up alkalinity when it is that low.

 

[shaun1985]

So what would you advise dose around 40-50ml of kh to get it upto 6 ?
That would be some spike

 

[Randy Holmes-Farley Verified Community Expert]

So what would you advise dose around 40-50ml of kh to get it upto 6 ?
That would be some spike

I don't know about the mL since it depends on what product and tank water volume, but yes, I'd raise it the 1.3 dKH to 6 dKH (if you are convinced it really is 4.7 dKH).

Try the kit on a batch of new salt water to see what you read there.

 

[shaun1985]

I don't know about the mL since it depends on what product and tank water volume, but yes, I'd raise it the 1.3 dKH to 6 dKH (if you are convinced it really is 4.7 dKH).

Try the kit on a batch of new salt water to see what you read there.

Ok will do thanks