Rough feeling on hot tub walls

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BigOrangeSpa

BigOrangeSpa

Gold Supporter
Oct 8, 2024
38
Brownsburg, IN
Hey all,

I think I've got my water pretty dialed in but every few days I'm noticing a rough feeling above the waterline of my hot tub. It extends pretty much all the way up the sides all around and on the top of walls too. I'm just trying to make sure this isn't scaling that I'm feeling. It wipes off really easy with just a towel and the surface is smooth again. It does almost feel like hard water deposits but my levels are:

CH: 175
TA: 80 (it was lower around 50-60 and then increased after needing to add quite a bit of fill water due to splash out. pH has stayed stable so I haven't bothered lowering it).
pH: 7.6 (really hasn't moved much -- it finally got up to 7.9 this morning so I lowered it back to 7.6 with 1 oz of Muriatic Acid, but that's the only acid I've had to use for over a week).
Borates: 50

I've kept my FC between 3-6 pretty religiously as well. Water looks great.

I am using Aqua Clarity weekly. Could it be biofilm that the aqua clarity is pulling out?
 
I am quite certain it is not biofilms. Is you tub acrylic or roto-molded? Just a question, why are you maintaining such a high chlorine residual? 3-6 ppm is more than what you need, especially with the AquaClarity. Unless the water temp is always 104degrees with the cover off and lots of usage, you should target 2.0 ppm.
 
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Ahhsomeguy said:
I am quite certain it is not biofilms. Is you tub acrylic or roto-molded? Just a question, why are you maintaining such a high chlorine residual? 3-6 ppm is more than what you need, especially with the AquaClarity. Unless the water temp is always 104degrees with the cover off and lots of usage, you should target 2.0 ppm.
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Thanks for the reply!

It’s acrylic. I am just following the sticky in this forum for the Dichlor / bleach method and it says 3-6 normally. It’s good to know that it can be lower with Aqua Clarity. I will stick closer to 2.
 
BigOrangeSpa said:
Thanks for the reply!

It’s acrylic. I am just following the sticky in this forum for the Dichlor / bleach method and it says 3-6 normally. It’s good to know that it can be lower with Aqua Clarity. I will stick closer to 2.
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I’m not saying staying closer to “2” is bad. My problem was when trying to do that, I often ended up at “1” or even “0”. I needed a cushion. I’d forget to add Cl on a night we didn’t use our tub. Your tub is gonna use Cl at a certain level. You won’t “save” Cl keeping it lower. My CYA is 40 and I always bump it to “7” when I add liquid pool Cl.
 
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I was understanding it similarly. I know CYA is helpful for preventing sun breaking chlorine down, but in hot tubs I was thinking of it as providing a way to run a higher FC level to have a buffer against reaching zero. So I've been trying to time it so it's always around 3 when I get in, and then I add enough to raise it back to 6. I've stopped testing before and after like I was doing at first and just check FC and pH once daily and I'm usually able to guess the FC level before the test so I feel like I've got a pretty good handle on how much my tub is consuming.

What I wasn't putting together is that Aqua Clarity should reduce the FC I'm running. I guess it makes sense as biofilm build up requires more chlorine. I am nervous about running it that low and forgetting to add it one night and then waking up with zero, especially having ozone.
 
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So, let me try to assist with what can happen with AquaClarity as well as using ozone. Aqua Clarity is constantly working to remove any particles that may be forming or clinging to any surface that comes in contact with the hot tub water. Providing a full and effective purge prior to using AC is a must. The AC will be providing ongoing mini-purges as buildups try to attach. This being the case, free chlorine levels can and will decrease as the sanitizer oxidizes or burns out bio-particulates. Once your tub has been using the AC for a few weeks the amount of chlorine loss should decrease in a normal soaking environment. I am positive that your hot tub water stays remarkably crystal clear every single day if you maintain adequate chlorine levels and add the required amount of AquaClarity weekly. Since you have an ozonator I would like to know if it is operating as a stand-alone appliance or if it is plumbed into the circulation system. Basically, does the ozonator run when your tub water is circulating? If so, and I suspect this is the case, you will need to keep the chlorine ppm at between 3-4. Ozone places a somewhat higher demand on chlorine levels as it converts HCL into chlorides.
 
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Ahhsomeguy said:
So, let me try to assist with what can happen with AquaClarity as well as using ozone. Aqua Clarity is constantly working to remove any particles that may be forming or clinging to any surface that comes in contact with the hot tub water. Providing a full and effective purge prior to using AC is a must. The AC will be providing ongoing mini-purges as buildups try to attach. This being the case, free chlorine levels can and will decrease as the sanitizer oxidizes or burns out bio-particulates. Once your tub has been using the AC for a few weeks the amount of chlorine loss should decrease in a normal soaking environment. I am positive that your hot tub water stays remarkably crystal clear every single day if you maintain adequate chlorine levels and add the required amount of AquaClarity weekly. Since you have an ozonator I would like to know if it is operating as a stand-alone appliance or if it is plumbed into the circulation system. Basically, does the ozonator run when your tub water is circulating? If so, and I suspect this is the case, you will need to keep the chlorine ppm at between 3-4. Ozone places a somewhat higher demand on chlorine levels as it converts HCL into chlorides.
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Absolutely. Water is always looking great. Since my last fill I've not had the water go even slightly cloudy.

Before filling this last time, I used the Ahhsome product (had some ordered before I learned about Aqua Clarity) and had a bunch of stuff come out. I had never done a purge before. I went ahead and did another round of Ahhsome and then drained it. I am confident I got most of the gunk out. I have been using 2 oz of Aqua Clarity weekly since. It's been 3 weeks since I purged.

My ozonator runs 24/7 with my circulation pump.
 

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I’m stumped as to what it may be with the numbers you’re posting.
Initially I thought it may be like my tub where above the water line is actually a different texture that you’re just noticing but you say it wipes away :scratch:
Can you gather some of this “debris” and place it somewhere that it would be safe to put a little muriatic acid on to see if it foams?
Is it hard & gritty or smooth & slimy/sticky?
 
Mdragger88 said:
Also, I see you’re using a ph meter.
Have you confirmed your ph with the phenol red test lately?
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Yep! I usually run the phenol red test a few times a week when I test and it always matches the meter. Haven’t ever seen the purple hue for 8.2 during this time. I have a bunch of the solution to calibrate the meter so I check its calibration often with that too.
 
Mdragger88 said:
I’m stumped as to what it may be with the numbers you’re posting.
Initially I thought it may be like my tub where above the water line is actually a different texture that you’re just noticing but you say it wipes away :scratch:
Can you gather some of this “debris” and place it somewhere that it would be safe to put a little muriatic acid on to see if it foams?
Is it hard & gritty or smooth & slimy/sticky?
Click to expand...
I’ll try that. I would say it’s closer to hard and gritty than smooth and slimy/sticky.
 
Well, it hasn't happened again since I posted (and also coincidentally lowered pH back down to 7.6). Is there any chance it actually was a bit of scale at 7.8/7.9? Seems irregular based on what I've seen posted here that it would happen at that pH for my other levels and with a negative CSI in PoolMath.

Something else I wanted to ask about -- I know my fill water has really high phosphates (> 3000). I've read here that generally the recommendation is not to treat phosphates or test for them because at the FC we're running it won't lead to algae. It seems like there is something called calcium phosphate scale, but it seems like my CH would need to be higher than 175 for that to be what's happening, right? Also, the description of it doesn't sound quite right online (hard to remove, white).
 
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