Alk consumption gone way down.

[JohnnyTabasco]

So I have been facing some difficulties lately and I would like some advice.

It all started with some negligence of the tank. My alk had been stable on 8.2 for a long time, so I stopped measuring for a couple of weeks.. and sure enough- it had climbed to 12.0 for no obvious reason.

I'm dosing the aqua forest 123, so I stopped dosing the alk solution and it slowly went down.
But when it hit 9 it just stopped taking up alk.
It was previously using 45ml a day. And now it's like 7ml a day.
My alk is now steady at 8.6ish and has been for 2 weeks.
My calcium is 53ml a day and magnesium is 40 ml a day.

The tank is 20g with mixed coral.
Ca: 400
Mg: 1350
Po4: 0.06
No3: 0.5
Temp 26.2

The corals are looking a little stressed out, but not dead. Only a Lobophyllia is looking like is going to die. Small patches of stn is happening - but fair enough.

So what could result in alk consumption just stopping like this when ca and mg still are being taken up as normal.
Any suggestions on what I should do about it?

 

[Crabs McJones]

What testing kits are you using to determine these levels?

 

[JohnnyTabasco]

What testing kits are you using to determine these levels?

Hey. It's Hanna for alk and po4.
Salifert for the rest.

 

[Randy Holmes-Farley Verified Community Expert]

It may take organisms time to ramp up their ability to consume alk at a lower alk level (they will have to increase their active transporters in their membranes), and you should expect considerably less daily demand for alk at 8 dKH than at 12 dKH.

 

[JohnnyTabasco]

It may take organisms time to ramp up their ability to consume alk at a lower alk level (they will have to increase their active transporters in their membranes), and you should expect considerably less daily demand for alk at 8 dKH than at 12 dKH.

Okay, thanks. But strangely enough I stopped dosing the alk solution and it's still climbing.
So I tested my rodi water with the hanna (don't know if it works?!) But it gave me 2.6 dkh.
Do you think that could have something to do with it?

 

[Cory]

Okay, thanks. But strangely enough I stopped dosing the alk solution and it's still climbing.
So I tested my rodi water with the hanna (don't know if it works?!) But it gave me 2.6 dkh.
Do you think that could have something to do with it?

Whats the tds of the water?

 

[JohnnyTabasco]

Whats the tds of the water?

I figured out that the alk was only in the ato container not in the rodi. So I cleaned it out and now I'm waiting to see if that was the problem.

 

[PSXerholic]

I figured out that the alk was only in the ato container not in the rodi. So I cleaned it out and now I'm waiting to see if that was the problem.

Sometimes it makes sense like in your case to perform an ICP test.
It might be that your calcification is down, hence much less ALK consumption.
This can happen from experience if certain trace elements are far too high or depleted so the calcification and metabolism of the Livestock is affected and with less ALK consumption and continuous dosing it starts to build up.

For the moment I would recommend to slow down dosing and let the ALK dropping very slowly.