Question anout scaling on a brand new SWG

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R

radefeld

0
LifeTime Supporter
Apr 6, 2012
109
Bonner Springs, Kansas
Hello all, I've been searching the site for answers, but I haven't found anything about my situation.

Background: About a month ago we replaced our pool liner due to age and a hole. At the same time (more or less) I moved all our pool equipment about 20 feet away and during the move process, since I was re-plumbing everything, I ordered and installed in a new Circupool RJ+60. I refilled the pool from our tap (TA:230, CH:210) and added in CYA, salt and liquid bleach until I had the pool ready to turn on the SWG.

I turn on the SWG on Monday, July 11th and it works like a champ - now time to get it set for the optimum chlorine level. On July 15th, I noticed there was some scaling in the cell (the body of the SWG is clear - and I like to take a peek!) so I investigated and found that if the Saturation index is off, it may cause some scaling. I don't recall my exact numbers because my wife cleaned my desk - but my TA was something like 230 since it was from the tap. I followed the direction on the TFP site and built a fountain to aerate from my return in the deep end
TqCYh4ub.jpg

Full image of Fountain from the side
and
W3jpEgJb.jpg

Full image of Fountain from the front
drop PH to 7.2 and aerate until 7.6, then repeat the process. I will admit, the fountain works WAY better than I thought it would and it will increase PH VERY QUICKLY and there were some times it was at 7.6-8.2 before I was able to hit it with the acid. I was out on a business trip the week of the 18th, and when I returned on the July 22nd, there was so much scaling on the cell that I can literally see the some of the channels were blocked. Saturday morning (7/23/16) I used the 1-4 water/muriatic acid mix called for in the manual to descale the cell, reinstalled, and it powered right up. I've been able to get TA down to 190 so far - but it seems like it's taking forever. With the fountain, I need a gallon of muriatic acid per day to keep up with the PH increase.

By Sunday night (July 24th) the walls of the cells are now starting to get scaling again and as of today (July 26th) you can definitely see the scaling again:
6z88UEZb.jpg

Full image of the cell

My water values today were:
PH: 7.2
TA: 190
FC: 7.5
CC: 0
Salt: 4200
CYA: 60
CH 210
TEMP: 88°F

which, when I plug this into PoolMath - I get a CSI of -.31

I'm trying to get my numbers within the Water balance for SWG guidelines, and struggling. So my questions are:

1) Does it take this long to decrease TA? It seems like a gallon of muriatic acid per day is a bit excessive, no? Is this normal?
2) Am I following the right path here - correct salt level -> Correct CYA level ->correct TA -> Adjust PH -> Add Borates?
3) From someone who has been in my shoes, is it obvious where I am screwing up? I have a feeling I'm letting my PH rise too high (i.e. above 8), too often - which is causing the scaling? How long does it need to be above 8 for scaling to start? I currently have been adding the acid in the morning, then checking again at night - do I need to do a noon check as well to keep the PH trend more even?

Thanks in advance, just going a bit nuts over here!
 
I used the recommendations from the Water Balance for SWGs article in Pool School:
Pool School - Water Balance for SWGs

It was:
To summarize:
FC 4-6 ppm
PH 7.5-7.8
TA 60-80
CH
50-300 for vinyl (Do Not Add)
220-320 for fiberglass
350-450 for plaster
CYA 70-80
Salt 200-400 ppm ABOVE recommended optimum level
Borates 30-50 ppm (optional)

I plugged these into PoolMath with the other targets for my Pool:
FC:4
PH:7.5
TA:60 (Which I would have a long way to go!)
CH:210
CYA:70
Salt:4200 (the manual calls for 3000-4000ppm - I went 200 above as recommended)
Borate:30
Temp:88

Which resulted in a CSI of -.71, You can also do pretty much the same if you go to poolmath and choose the settings at the bottom:
Use suggested goal levels from: TroubleFreePool.com
Primary source of chlorine: SWG
Pool surface: Vinyl

If I leave my TA where it is at 190 - all other setting above held the same, my CSI would be -.03 - but this is effectively where it's at now (minus the borates) and I'm seeing the scaling.

Thanks for the help! :)
 
You're welcome. I see the edit to negative. The high positive CSI was what I was concerned about. It is fine to go more negative on CSI in a vinyl pool because you don't have to worry about etching. If it were a plaster pool etching is a concern but your CH would be higher to offset it. You are too close to 0 and the PH is higher in the SWG cell which is why you still have some scale. I missed that it was vinyl in the first post, I would be more aggressive with your CSI. More like -0.3 or less.

You should lower your PH to 7.2 when it gets to 7.5. The lower PH will lower your CSI and the acid will slowly lower your TA. As TA drops the upward pressure on your PH will reduce.

It would probably be worth the effort to spend some time actively lowering your TA when you are hanging out in the pool on the weekend. Here's how, Pool School - Lower Total Alkalinity
 
With a TA of 60 and those numbers above you get a CSI of -.7


To be honest I'm a little surprised by how quickly you are scaling with such a low CH level. But it's worth noting that the environment inside the salt cell is very very different place than what Pool Math is calculating too. It would seem consistent to think that a high TA level would cause an increase in CO2 outgassing inside the cell which could easily cause the local PH inside the cell to be much higher than it otherwise would with a similar CSI number (lower TA, higher CH) (That's more speculation than fact - but it makes sense)

Long story short - you may find your scaling problem reduces as the TA gets closer to 100
 
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