UKH

I'm in the process of making a hot tub and started doing some research into chemicals, but I've found it a bit of a minefield of different products. 

I'm keen to avoid chlorine based products as my eyes and skin sometimes reacts. 

What products can folk recommend?

Aren't fake tan, baby oil and semen the normal 'chemicals' found in hot tubs?

Do you mean "a sex pond "?

... And a splash of prosecco! 

Cross your fingers for me 

Will you hot tub be constantly filled with water?  or will it be a small wooden one?

If the latter, dont bother and change the water after each use/ couple of days.

If the former, go to a hot tub company shop/ website and get some tabs- I think they do 'eco' ones without chlorine..  they might not be great without a pumb to mix the water around- buyt again that depends on your build.

It made from an IBC container with the top cut off and I'm going to insulate it and wood clad it. I've fitted 2 tank connectors which are connected to a copper coil that is inside a chimnaya which I'll pump and I've got aquarium heaters that will keep it at 34c. As it'll have 5-600l of water I'd prefer to use the water for longer so I use less. 

Nasty sex pond, to use the full phrase

Personally I would say that's small enough to empty after every use- but it depends on how often you are likely to use it.... and the size of your heaters.

Also depends on how accurate you are planning to be with your chemical cleans.  At least by re-filling every time you are guaranteed of cleanliness. 

I wonder if you could use a couple of those 3 stage under counter water purifiers to do the cleaning instead of chemicals?

I'm not certain but it maybe worth some research. 

As I understand it, it isn't the chlorine products that cause issues, it's when they mix with all the nasty stuff from people.

So it may be that if you avoid having dirty people in your tub chlorine will be fine. 

We used to have a communal hot tub in Trawsfynydd village. A few chemicals in the water never bothered us...

My favourite was a metal tub at the Yosemite Bug that was zero chlorine, with a low level of peroxide and a UV treatment system.

My take is that it's better to have an ultra-low chlorine system with a multi-wavelength UV system  The UV both destroys microbial stuff and busts apart the smelly chloramines formed when chlorine binds to all the organic crap in there.   It sounds like this is more effective and it avoids the skin and eye issues of normal chlorine levels, some of which are down to the chloramines.

The issue for me is that UV bulbs are nasty and short lifetime and don't take kindly to being turned on and off a lot so are an energy sink.  The bulbs can also shatter and feed glass shards into the plumbing.  With the way UV LED development is going I think we'll see LED devices in a few years which will address all these issues. 

Then you get in to the question of filters.  Proper filtration seems to make a big difference. My current (and first) hot tub is a small green Lidl paddling pool modified to circulate water through a very course outtake screen, a coarse Y-strainer, a small paper cartridge fine filter and an 80 litre wood burner from Eldom [1].  We don't use it often and when we do it's single use tap water that's then drained into the garden.  The filter gets cleaned after each use; the water temperature is pushing the manufacture's specs for the filter cartridge.   Before and after photos below.  This uses a little 24 V DC pump running of an isolated supply and an inventive mix of "Hozelock" style hosepipe plumbing, a shower hose, 32 mm metric solvent-weld PVC pressure pipe and 38 mm flexible hose.  The latest iteration has eliminated the 1/2" BSP bulkhead connector running through a solvent-weld end stop and all self-amalgam tape, it's almost professional like...

[1] https://www.amazon.co.uk/Heater-Burning-Boiler-Enameld-Vertical/dp/B06W9DWJ...

The Num Num’s hot tub is 90% urine 

If you're building a hot tub I hope you'll be fitting it with a silencer; we have hot tub neighbours and it's a pain in the 'arris when they are out shouting and laughing in their tub at midnight. 

Make sure there are no dubious Russian energy drinks near the console