Trouble maintaining alk

[reely989]

I have a 300 gallon system that is still new and I'm having a hard time maintaining alk. I'm hoping it's because coralline is taking hold and it'll get easier but I'm dosing 375ml of Randy's hydroxide recipe a day and still finding myself having to supplement with bicarb a lot. It was 6.3 a couple of days ago and I added 500ml of bicarb and I tested today and it was down to 6.1 despite that and my regular dosing. Am I missing something or is this need typical for a tank this size?

 

[Mr. Mojo Rising]

Down only .2 "in a couple of days" is not a big deal. But you dosed something so the real consumption is unknown. You would need to test every day (without dosing anything) around the same time of day, to get a real read on how much the alk drops per day. Once you have that info, then you can create a proper dosage plan, there are several ways to maintain the alk, it depends how much your tank consumes daily.

 

[Randy Holmes-Farley Verified Community Expert]

I have a 300 gallon system that is still new and I'm having a hard time maintaining alk. I'm hoping it's because coralline is taking hold and it'll get easier but I'm dosing 375ml of Randy's hydroxide recipe a day and still finding myself having to supplement with bicarb a lot. It was 6.3 a couple of days ago and I added 500ml of bicarb and I tested today and it was down to 6.1 despite that and my regular dosing. Am I missing something or is this need typical for a tank this size?

Well, let’s figure out how much alk you are dosing.

If the hydroxide is my recipe, that is adding about 1.8 dKH.

The bicarb (if my recipe) is adding about 1.5 dKH.

If alk is lower than you want and you are not seeing substantial precipitation (hardening sand, etc.), then raising the dose of the hydroxide or adding the bicarb more often seems a fine plan to me.

 

[reely989]

Well, let’s figure out how much alk you are dosing.

If the hydroxide is my recipe, that is adding about 1.8 dKH.

The bicarb (if my recipe) is adding about 1.5 dKH.

If alk is lower than you want and you are not seeing substantial precipitation (hardening sand, etc.), then raising the dose of the hydroxide or adding the bicarb more often seems a fine plan to me.

I guess I just feel like it's a lot of demand for a new system. My pH is running a little on the high side too from so much hydroxide and I run a CO2 scrubber. If I swap to your soda ash recipe is it soluble enough to mix up at 1.5x or 2x concentration? Is there any downside to doing that?

 

[reely989]

Down only .2 "in a couple of days" is not a big deal. But you dosed something so the real consumption is unknown. You would need to test every day (without dosing anything) around the same time of day, to get a real read on how much the alk drops per day. Once you have that info, then you can create a proper dosage plan, there are several ways to maintain the alk, it depends how much your tank consumes daily.

I know it isn't a big deal. I'm more surprised that a new system is consuming so much a day.

 

[Merge_595]

I have a 300 gallon system that is still new and I'm having a hard time maintaining alk. I'm hoping it's because coralline is taking hold and it'll get easier but I'm dosing 375ml of Randy's hydroxide recipe a day and still finding myself having to supplement with bicarb a lot. It was 6.3 a couple of days ago and I added 500ml of bicarb and I tested today and it was down to 6.1 despite that and my regular dosing. Am I missing something or is this need typical for a tank this size?

https://www.avastmarine.com/products/kalk-stirrer375 ml is a lot this saved me a lot of headaches

 

[Morpheosz]

Maybe double check your test kit? I have used the Hanna digital checker for the past 3 years and it's been super reliable. For comparison, I have a 3 year old 75 gal that is wall to wall packed with mature growing corals and I add ~100ml/d of soda ash to maintain 8.0.

 

[reely989]

Maybe double check your test kit? I have used the Hanna digital checker for the past 3 years and it's been super reliable. For comparison, I have a 3 year old 75 gal that is wall to wall packed with mature growing corals and I add ~100ml/d of soda ash to maintain 8.0.

I use the hanna as well but that has crossed my mind too

 

[Reign1]

had lower Alk , went to hydroxide in ATO and boom stable alk now.