Trichlor and Bleach

[jay87]

I am currently using Trichlor and MPS shock in my hot tub. I was considering switching to using sodium hypochlorite instead, but do I have to totally eradicate the trichlor or can I mix them? I have read that mixing it with anything slightly acidic creates a chlorine gas which I don't want! Thanks in advance

 

[JasonLion]

Welcome to TFP!

Mixing full strength acid and bleach (or trichlor) in a bucket is very dangerous. Adding acid and bleach, in reasonable quantities, separately to the tub is totally safe.

You can just start using bleach right away. There is no need to do anything special.

 

[jay87]

That's great! Just what I wanted to hear. Think I will give it a go and let you guys know how I get on I only heat my spa around 3 days a week and it's kept covered, so hopefully chlorine loss won't be too much

 

[chem geek]

Since you have been using Trichlor and MPS which are both acidic, your Total Alkalinity (TA) level is likely to be high in the tub to try and keep the pH from falling too much. If you switch to bleach, that high TA level is going to have your pH rise a lot, especially if you have a lot of aeration in your spa such as from running jets. Read Using Chlorine in a Spa to learn about how to properly use bleach. You may need to significantly lower your TA level to get pH stability. You should also test your CYA level, though I would assume there is some in the water given your Trichlor usage. Also, get yourself a proper test kit if you don't have one already (see Test Kits Compared for the two recommended test kits).