Thinking of doing a cheap ozonator experiment. Could use some advice

[DangerBoy]

I'll soon be receiving an starting up a very nice condition vintage 1995 Hot Springs Grandee. It has a Watkins Fresh Air II Ozonator system in it that's long past its day and no longer works. I would like to have a working ozonator in the tub if possible but due to the economic circumstances I'm in, I have to do it on the super cheap so spending even a couple hundred to replace it with a third party Ozonator is not really an option for me so I've been searching for ways to get an ozonator working in the tub as cheaply as possible. Here's what I'm thinking of doing:


I can get a cheap Chinese corona discharge ozonator that's supposedly rated at 200-400 mg/hr at 40% RH for about $15 USD shipped on AliExpress. Below is a link to the ad: The flow through on the unit is rated at 3.1 L/min.


Link to cheap CD Ozonator


I know that even 200 mg/hr is way more than what the OEM Fresh Air II and III systems put out but I only halfheartedly believe the output rating quoted in the ad. To be safe, I'm going to assume it's at best 1/2 of that so maybe 100 - 200 mg/hr. Then I have to take into account the loss of efficiency due to operating in a somewhat humid environment. With all that taken into account, I'm guessing that little unit will only put out 70 or 80 mg/hr which I think is still a lot more than required for a 500 US gallon (1,890 L) tub. Unless I'm mistaken, I think the OEM Fresh Air II unit that came with it was only rated at something like 35 mg/hr.


I figure that to make the unit last longer and to avoid pumping more ozone into the tub than necessary, I could put it on an infinite loop repeat cycle timer so it doesn't run all the time. The question is, what would be a good on/off cycle to try first? Something like 5 minutes on/5 off? 15/15? 1 Hr/1 Hr? For something like $10 - $15 USD shipped I can get a repeat cycle timer in a water resistant case on AliExpress that will let me program in just about any on/off cycle I want.


In case other information is needed, the Silent-Flo 5000 24 hr circulation pump on the tub is rated at 3-5 US gal/min which is 11.4 - 19 L/min in real units. and the tub supposedly has an 8 - 10 foot long ozone kill chamber downstream of the circ pump.

If we assume the output rate of the circ pump is the average of the rated range (4 USgpm) it would take 125 minutes to circulate one full tub volume. Would then 125 minutes on and say 100 minutes off be a good cycle to try? It should be kept in mind that some of the water in the jet lines, etc, probably isn't being circulated at all through the circ pump so it's not like all of the water in the tub actually goes through the circ pump every 125 minutes. Some of it isn't and some is going through at least twice during that time.


For $20 USD shipped on the ozonator I figure there's not much risk in giving this a try. I'm not expecting a real long life on these ozonators but for $20 I wouldn't mind if I had to replace them one once a year and if I get two or more years out of them I'll be super happy. I figure I'll always buy two at a time so I'll always have at least one spare on hand.


Does this sound like a worthwhile experiment or are there some hidden dangers here that I'm not seeing? Is anyone interested in seeing how this experiment turns out? I could document and put postings on the installation and results if people are interested to know how it turns out.


TIA for your feedback and ideas.

 

[jseyfert3]

Unless you are using bromine, ozone isn't recommended on TFP. It distroys FC and provides no advantages. Chlorine is litterally the only sanitizer/oxidizer you need, and the cheapest one too.

Ozone can be useful in a bromine spa as it will reactivate bromide back into hypobromous acid.

I may as well mention UV. This is occasionally recommended for indoor spas/pools to help break up certain CCs, but only on a limited basis and not continuously as it too breaks down FC. For an outdoor spa you can just open it to the sun to get some UV if your CCs get high.

You seem to be resistant to the advise you're getting on this forum (MPS thread). You're of course welcome to take it or leave it, but since you mentioned financial concerns, here's some financial advice: Try the TFP method. Skip the ozonator and MPS (or DPS or whatever that other stuff was). The money you'll save will pay for all the acid and chlorine you'll need for over a year, and probably the recommended test kit too. An entire year of bleach as your only sanitizer/oxidizer will only use about 4 gallons of 8.25% bleach. That's about $10. Economically, you can't beat it.

 

[DangerBoy]

I may as well mention UV. This is occasionally recommended for indoor spas/pools to help break up certain CCs, but only on a limited basis and not continuously as it too breaks down FC. For an outdoor spa you can just open it to the sun to get some UV if your CCs get high.[/COLOR]

You seem to be resistant to the advise you're getting on this forum (MPS thread). You're of course welcome to take it or leave it, but since you mentioned financial concerns, here's some financial advice: Try the TFP method. Skip the ozonator and MPS (or DPS or whatever that other stuff was). The money you'll save will pay for all the acid and chlorine you'll need for over a year, and probably the recommended test kit too. An entire year of bleach as your only sanitizer/oxidizer will only use about 4 gallons of 8.25% bleach. That's about $10. Economically, you can't beat it.

Okay, I will skip the Ozonator idea. I didn't know it was detrimental to free chlorine levels.

On the UV thing, how long would I have to leave the tub open to sunlight to break up CCs? I don't know if I'm in love with having to open the tub for several hours during our winter months when the UV levels are low and so are air temperatures. Could it possibly be worthwhile to install a cheap UV water sterilizer system for that purpose? I can get a cheap 36W system that's rated for more throughput than my circulation pump puts out on AliExpress and put it in line with the circ pump. Then, if I ever have high CCs I need to deal with, I could turn it on for just long enough to break up the CCs whenever I need to. I guess the question is, how often am I likely going to need to do that?

 

[jseyfert3]

I'm not sure. With our indoor (garage) inflatable spa, I haven't had much of an issue with CCs, and I have zero UV. One time with a long period of back to back (daily) LONG soaks I did start to get some CC smell. Otherwise it hasn't been a big issue.

I've read from other people maybe an hour or two, but it's really only if you actually start getting CC buildup that's problematic. I'd recommend waiting to see what actually happens, you can always add UV later on if desired. Otherwise if the CCs stay in check you're good.