Salt Water Hot Tub Issues

[HouseLamp]

Hi all,

I'm new here on the forum and hope to find a solution for my hot tub issues between all the great minds on here and contribute any input on issues that arise!

I operate a commercial hot tub system and I'm also a certified pool operator.

The hot tub is a fibreglass 792 US Gallon tub and uses a Low Salt Water Cell combined with a Hayward ProLogic CAT controller.

I'm having a consistent battle with balancing the tub. It's drained and cleaned every week, probes cleaned monthly.

Chlorine:
The ORP never truly sits at a consistent reading, when you think its a steady ORP 795 for example and Total Chlorine is at 4ppm, hours later the chlorine could be 10+PPM and ORP 850.
If i try to be conservative and set the ORP at 750 and the Total Chlorine is at 4ppm, hours later the chlorine can be 0.2ppm and the ORP at 790, therefore not creating any. I understand the effect of adding alkalinity, and that driving down the ORP temporarily...etc

Alkalinity:
It rapidly reduces on an hourly basis, from 150ppm to 4ppm after only 10 or so people have used it. The acid is diluted from anywhere from 30% to 80% with water. Having no luck in the alkalinity at least being more stable or longer lasting. I go through so much of it!

Salt:
I use the correct calculation to add salt after the hot tub has drained and filled, 1200ppm is the desired number, but by the end of a week it can be over 3000ppm with no salt added...?

I run a number of other standard chlorine and acid style hot tubs and i can test and troubleshoot them with my eyes shut. Very simple systems. But i'm new to salt and after studying the CAT controller functions, doing all things by the book, this salt water hot tub does not seem to sync up. I'm either in need of some tips or i feel the system is just not meant to be used for a heavy used commercial hot tub.

Fibreglass shell:
I've noticed now a aqua blue/green staining around the skimmers and baskets. It comes off with our weekly clean and takes a few days to show. Also a waxy residue in and around the tub, hard to see when its full but when its empty it's quite noticeable, I've shocked the hot tub on multiple occasions for 24hrs, i weekly drain it and this staining is hard to remove, in fact it barely comes off. I have scrubbed with acid once before and this waxy residue has sank into the etching from the scrubbing pads.

I'm really at a loss now, it's been a year of closely monitoring and seemingly getting nowhere. I take pride in the hot tubs i run but this particular one is just getting the best of me. I can provide pictures of said staining and anything else.

Thanks in advance!

 

[HouseLamp]

Hi,

I've attached some pictures here to see what you guys think this is?

Couple of issues, as you can see the tub is covered in what feels like a waxy/greasy film. VERY stubborn to remove and to be honest i now just clean 'over' it. It's a Salt Water tub and fibreglass shell. Emptied every week and cleaned, it's outside and covered.
I've shocked the tub on multiple occasions and i believe i did wash it down many months ago with straight acid, which resulted in a clean tub. But now the wax/grease has returned, it has brought out where i cleaned with acid, etch lines made from my scrubby pad...

The other is a aqua blue tinge around the top of the water line, stains the skimmers and water line but is easily removed with normal sponge clean.

Any thoughts on this? I did think an algae issue at first but i now believe it could be a more complex/niche issue?

Thanks for any suggestions!

 

[Newdude]

Looks bio-film-y. Try several ahhh-some purges and if nothing else you will know the internals and plumbing are sterile.

 

[HouseLamp]

Thanks for your response. It kind of does, it covers the whole tub below water line, not just the top water line. It's had three 24hr shocks and gets emptied and scrubbed with chlorox on a weekly basis. It's only a year old!

I wonder if its the gaskets or glues/silicones breaking down under the salt water system and its mixing with the water and clinging to the shell. Far fetched i know but i'm at a loss!

 

[Newdude]

I would vote for people. We are disgusting things. Body oils, sweat, dead skin, residual shampoo/conditioner....... I thought bathing suits were clean fresh from the dryer until I got my hot tub and they turned it into a bubble bath each time from detergents and fabric softener....... the eight Margarita is way spillier than the first, no idea why but it is. Lol. I could go all day. Anyway even from the factories they tubs come gunked up and it only gets worse with use. It may take a few purges to loosen whatever is gummed up but when it comes out it is NASTY. It needs to come out either way and it will probably even fix your issue. Win-win. Or at least you know what it isn’t.

 

[Newdude]

@jseyfert3 would you be so kind to link your purge thread, I’m having difficulty finding it at the moment. Thanks.

 

[jseyfert3]

Emptied every week and cleaned, it's outside and covered.

Every week!? Is this a private or public hot tub? If this is a private tub, that seems very excessive.

The blue is interesting. What are you adding to the water?

@jseyfert3 would you be so kind to link your purge thread, I’m having difficulty finding it at the moment. Thanks.

Yeah that's cause I ended up sticking it in my pool build mega-thread. Maybe I should copy that over to a new thread here in the hot tub section. 26' Intex - Planning, Install, Upgrades, and Landscaping Thread (Ahh-Some Spa Purge)

 

[HouseLamp]

Every week!? Is this a private or public hot tub? If this is a private tub, that seems very excessive.

The blue is interesting. What are you adding to the water?


Yeah that's cause I ended up sticking it in my pool build mega-thread. Maybe I should copy that over to a new thread here in the hot tub section. 26' Intex - Planning, Install, Upgrades, and Landscaping Thread (Ahh-Some Spa Purge)

Its public, so i empty it every week and send water samples off. Right now it's used gently because of Covid restrictions but it can often get 10hrs of use from anywhere from 2-10 people non stop so the combined readings can be high towards the end of a week.

Other than the salt added, we add alkalinity, muriatic acid which is on a sense and dispense system, we mainly just calibrate pH on the CAT. A tiny bit of Foamaway is added but only occasionally.

I see the post about people's oils and soap, but the waxy film over the top of the shell will not budge, it seems more than oil build up. I'm afraid of using acid too much in case i truly etch away the finishing paint on the fibreglass shell. I've just ordered Ahhh-some and stiff brush attachments for a drill, i'll try a degreaser to get the film off but even when i've had it off in the past, this film comes back. Pine needles do get into the system but not many. As mentioned, i wonder if the internals are breaking down from the salt. The hot tub installer is quite a hard guy to communicate with and quite frankly i'm done with him.

 

[jseyfert3]

Ah that makes sense for the quick water changes. Hopefully someone else here might know what your issue is.

 

[Mdragger88]

After your purge & clean try to maintain fc on the upper end of the chlorine side of the FC/CYA Levels w/ the swg.
to combat the heavy bather load.
like shock level when not in use as it will drop substantially when someone enters the tub especially if they haven’t showered or rinsed their suits, wear lotions, etc.
what are your normal running levels?
Fc
Cc
Ph
Alk
Cya
Ch

 

[HouseLamp]

After your purge & clean try to maintain fc on the upper end of the chlorine side of the FC/CYA Levels w/ the swg.
to combat the heavy bather load.
like shock level when not in use as it will drop substantially when someone enters the tub especially if they haven’t showered or rinsed their suits, wear lotions, etc.
what are your normal running levels?
Fc
Cc
Ph
Alk
Cya
Ch

We operate usually at this:

Fc 4-5ppm
Cc 0-1.5
Ph 7.2
Alk 100-180
Cya and Ch we don't test for.

We have the system set up as a sense and dispense, so the levels rarely change other than alkalinity. It's hard to manually adjust the Ch levels between bathers as we never know when they will enter, so raising them Ch to 9-10ppm can casue staining of bathing suits..etc We do have issues with the ORP being all over the place, but i believe that's another issue all together. Had no luck with this hot tub at all since Day 1. I run 2 other Chlorine and Acid set up tubs and they're perfect but this Salt Water set up is just issue after issue.

 

[Mdragger88]

Are u allowed any cya since its a public tub? Is it covered? Outdoors or indoors?
ch is an important # to know so you can track your csi in PoolMath
- also having 100-150 ch can help with the foaming although if you’re changing your water weekly it would probably be a pain to keep up with but u still need to know what you’re working with.