More Hot Tub Ideas

I've been working on a towel warmer for out by the hot tub. If it doesn't burn down my house I'll probably make a post about it. I am also looking into automatic dispensing of chlorine and boric acid though I wanted some feedback first.

Towel warmer

This is essentially an insulated box with a solid state relay controlling an electric heater to keep the box in a toasty temperature range. I need to play around and see what temps will work well but I've currently got the heater shutting off at 130°F...

Automatic chemical dispensing

I've been playing around with peristaltic pumps and they're pretty cool. I have cheap and easy access to 10% bleach and I guess I'll be dissolving boric acid powder into water. Would still need to occasionally manually add CYA and oxidizer, oh well.

When to add?

• Only during the filter cycles? That way you wouldn't need automated pump control to ensure circulation.
• For those with automated pump control I could publish when chemicals are being added and you could use Node-RED/HA automation to circulate when necessary.

How to prevent dispensing when the tub is in use?

• Disable if the cover is open?

Freezing temps?

• Boric acid and bleach freezing in winter? Additional circulator pump?
• Or storing the chemicals in the tub cabinet? That would also protect them from the sun but would be more of a pain to access.