Affects of diluted HCL on a reef tank

[Faithbleed]

I've been running a KHD for around a year now (tanks 2 years old).

I switched out the reagent for the DIY option (0.1N HCL) and have been using that since with no issues.

I chose to put the waste back into the tank as from everything I've read it seems like a mostly safe option.

Because I got a bulk lot of HCL and it's dead cheap I boosted testing to 8x a day.

I've just recently put together that when I increased from 4 to 6 and then to 8x a day, each testing amount increase brought with it an increase diatoms and cyano on the sand.

For what it's worth I already carbon dose with Aquaforest Nitraphos Minus and run GFO+Carbon.

- Would diluted HCL (KHD waste) act as a carbon source and thus be creating the diatom and cyano issues I'm now experiencing)?
- Would the diluted HCL increase or decrease PH?

For now I've halved my carbon dosing and wound back to testing 6x a day, but would be interesting and what others think.

 

[AJsReef]

I'm not a chemist, but it seems unlikely the diluted HCl would cause any issues. How much waste does each test produce?

 

[Randy Holmes-Farley]

Carbon sources do not drive diatoms. Think of them like green algae that uses silicate.

HCl is not a carbon source.

Adding the titration effluent back to the tank is like adding a small amount of zero alkalinity seawater. It wil have a small pH lowering effect, and alk lowering effect. How much depends on how much you dump back to the tank each day.

Whether any impurities are an issue will depend on the purity of the HCl you are using.

 

[Faithbleed]

I'm not a chemist, but it seems unlikely the diluted HCl would cause any issues. How much waste does each test produce?

I believe it's 100mL total, but not sure how much of that is the HCL part.

 

[Faithbleed]

Carbon sources do not drive diatoms. Think of them like green algae that uses silicate.

HCl is not a carbon source.

Adding the titration effluent back to the tank is like adding a small amount of zero alkalinity seawater. It wil have a small pH lowering effect, and alk lowering effect. How much depends on how much you dump back to the tank each day.

Whether any impurities are an issue will depend on the purity of the HCl you are using.

Thanks Randy, that's the answer I'm looking for.

I'm using Analytical Reagent (AR) grade.

 

[Sean Clark]

What is your "recipe" that you are using to mix up your DIY reagent? I want to try it out.

 

[Faithbleed]

What is your "recipe" that you are using to mix up your DIY reagent? I want to try it out.

I based it off of a thread I saw on here.

If you can get 0.1N HCL, just use that exactly as is as a official reagent replacement.

I could only get 1N, so I dilute mine down using 900mL of RODI water then add 100mL of 1N HCL to get a useable reagent.

I went a bit overboard and got glass beakers and measuring vessels to do it as accurately as I could.

No issues since.

 

[Sean Clark]

Thanks.