Spa chlorine usage and Ahhsome in pool

[jfdid]

Hi folks, I've been a pool owner using the TFP philosophy happily for 7 years and love this forum.
I bought a 10 year old used hot tub/spa a month ago(tub was running & hot when I bought it, was only drained for ~10 hours before it was back up and running). Filled it, ran bromine for 2 weeks then started reading up on TFP.
After initial 2 weeks, I purged with Ahhsome, and there was a little bit of crud, but nothing too gross.
Then filled and used the dichlor/chlorine method. I was using a fair bit of chlorine so I set my target FC to ~6ppm so it wouldn't drop down to 0. I bought an SWG - Chloromatic Chlormaker and it's been running at 10/10 for 2 weeks. But I still find the FC drops from 6 down to 1 after about 8 hours(day or night, and it's got a cover).

Questions:
Should the Chlormaker keep up with regular chlorine demand? (I understand I'll still have to add liquid chlorine after each soak, I'm more wondering if it should produce enough chlorine in 24 hours to no require additional chlorine, except if we soak).
I assume you'd recommend another purge, even though I did one 3 weeks ago? Would you shock it first or just keep FC at 5/6ppm and purge?
Can I drain the hot tub into my adjacent pool for the purge? I'm in Canada, the pool is currently stagnant and green because it's winter, so I'm not worried about it clouding the water - more worried about if having Ahhsome in the pool with mess anything up when I open it in the spring.

Thanks, as always

Hot tub ~ 1000 gallons.
Salt: 1500ppm
FC: goal ~6ppm
CYA: 16 (by calculation of dichlor additions)
pH: 7.3
TA: 100

 

[ajw22]

Getting Ahhsome in your pool should be fine. @Ahhsomeguy can confirm.

 

[PoolStored]

Chloromatic Chlormaker and it's been running at 10/10 for 2 weeks.

Running any cell at 100% is the quickest way to destroy a cell. We don't recommend running more than 90%.

Should the Chlormaker keep up with regular chlorine demand? (I understand I'll still have to add liquid chlorine after each soak, I'm more wondering if it should produce enough chlorine in 24 hours to no require additional chlorine, except if we soak).

Chlormaker makes .0661387 lbs/day. (from here, 30g per day...https://www.controlomatic.com/chlormaker/)

In your 1000 Gallon tub, that would be 7.9 FC if it is running 10/10 for 24 hours. Not sure what your FC demand is, but FC demand will be more with hot water. CYA degrades, so unless you test CYA, you don't know what your CYA is...

I would think that 7.9 would be enough...Maybe you turn it off for a couple days and maintain with liquid chlorine and see what your daily demand is...It is not uncommon for a unused hot tub to lose a few ppm per day but only you can determine the FC demand.

After your fresh refill you need to start off using Dichlor (which you know), not bleach, so that you build up some CYA. You cumulatively add around 33-444 ppm FC using Dichlor (usually takes about a week, depending on bather load) and then you switch to using bleach. About once a month, you use Dichlor for a day to make up for CYA loss.

So, it is not clear if you have an issue with cell because you've been running it at 10/10, or your FC demand is very high and needs to be corrected with purge/replacement or SLAM. I'd turn off the cell, and see what your daily demand is....If it is high, then purge/replace or SLAM, if it is low, your cell is not working properly.

 

[jfdid]

Thanks @PoolStored I'll drop the cell down to 90% this morning.
It's only been 3 weeks since the purge, so I'd assume the CYA level is still good. And 2 weeks since I started using the SWG.
I guess I'm trying to decide whether the SWG should cover the FC needs on days we don't use the tub, or if I have to add bleach daily regardless.
Or maybe the purge didn't get everything, but I also didn't see a lot of junk come out either.
If @Ahhsomeguy advises the purge water(with Ahhsome) can be dumped into my pool, with no ill effects come spring, then I'll probably just do a purge to be sure.

 

[PoolStored]

I guess I'm trying to decide whether the SWG should cover the FC needs on days we don't use the tub, or if I have to add bleach daily regardless.

I think it should. The only way to tell is to figure out your FC demand. If your FC demand is high, you have organics going on. If your FC demand is low, then there is something wrong with the cell.

 

[jfdid]

Oops - my hot tub is 1000 Litres!! Not Gallons. So it's 260 Gallons. Now that it's 4x reduced volume, do you think the SWG should keep up on normal usage days?
You're right, I need to determine & log the liquid FC usage to determine if the SWG is working. It's brand new and bubbling lots, but I should still check it.

 

[PoolStored]

If its bubbling then is is likely working. Yes, should handle a 260 G tub...

Let us know how the testing goes.

Likely that your fc is consuming organics left behind in your tub.

You must replenish the fc that is used up during each use + enough to maintain min for your cya FC/CYA Levels until you wish to use/check on the tub again. This could be a little or alot depending upon bather load, length of the soak, & organics present on said bathers & their suits. Obviously your tub volume plays a factor here as well along with whether or not u have uv or ozone. 2 bathers in my small tub for 45 + minutes can eat up 4-6 ppm.

My guess is that your FC got low for your CYA, and there’s no telling how long your fc was below min for your cya but every minute after that occurred you can bet that organics were proliferating...and the cell can't keep up.

 

[Ahhsomeguy]

Hi folks, I've been a pool owner using the TFP philosophy happily for 7 years and love this forum.
I bought a 10 year old used hot tub/spa a month ago(tub was running & hot when I bought it, was only drained for ~10 hours before it was back up and running). Filled it, ran bromine for 2 weeks then started reading up on TFP.
After initial 2 weeks, I purged with Ahhsome, and there was a little bit of crud, but nothing too gross.
Then filled and used the dichlor/chlorine method. I was using a fair bit of chlorine so I set my target FC to ~6ppm so it wouldn't drop down to 0. I bought an SWG - Chloromatic Chlormaker and it's been running at 10/10 for 2 weeks. But I still find the FC drops from 6 down to 1 after about 8 hours(day or night, and it's got a cover).

Questions:
Should the Chlormaker keep up with regular chlorine demand? (I understand I'll still have to add liquid chlorine after each soak, I'm more wondering if it should produce enough chlorine in 24 hours to no require additional chlorine, except if we soak).
I assume you'd recommend another purge, even though I did one 3 weeks ago? Would you shock it first or just keep FC at 5/6ppm and purge?
Can I drain the hot tub into my adjacent pool for the purge? I'm in Canada, the pool is currently stagnant and green because it's winter, so I'm not worried about it clouding the water - more worried about if having Ahhsome in the pool with mess anything up when I open it in the spring.

Thanks, as always

Hot tub ~ 1000 gallons.
Salt: 1500ppm
FC: goal ~6ppm
CYA: 16 (by calculation of dichlor additions)
pH: 7.3
TA: 100

Sure, ok to drain into pool. I do recommend another purge based on your chlorine loss. How much use before chlorine level slips to 1 ppm? If you are running at 6ppm (too high by the way), s/b @ 2-3 ppm, and it drops to 1 after a 2 person dip, you still have gunk in the plumbing. Before you dump the water let the Ahhsome stay in your tub for 8-12 hours if you can. Shut pump and jets down. Wait the 8 hours and turn back on high jets for 5-10 minutes. Shut system down. Wipe the shell and dump the water. Refill and start pump. Do this only if the temperature allows it so no pipe freezing. Such a short duration with pump off and hot or warm water prior to purging should not be an issue.

 

[jfdid]

Thanks to all who replied.
An update for future readers.
I ended up purging yesterday and am happy with the results today. I also removed all of the jets and cleaned out each jet/housing. There was some nasty junk in there so I imagine that was contributing to the FC usage.
To recap the issue:
My chlorine usage was quite high prior to the purge - I didn't map it out, but I was adding about 12ppm FC liquid bleach on a normal day, PLUS 4ppm any time we soaked. AND I had the SWG/chlorinator going at 100%(which is an additional ~30ppm/day). So 42ppm per day usage.
I hadn't actually SLAMed the tub, but I shocked it and kept the levels up at 6ppm(with 16ppm CYA). This was ongoing for a couple of weeks. I think I probably let the FC drop to zero overnight at some point and could never catch up with the bacteria/algae.

Anyway, the purge went well, I wouldn't say the amount of junk was amazing, but there was definitely enough that made me feel like it was the right call, eventhough the last purge was only 3-4 weeks prior.
I'm almost at 24 hours now, and my FC usage has been ~5ppm and NO chlorinator.

Looking forward to cleaner soaks and less maintenance.
Cheers