White flakes in pool from SWG / Phosphates : YouTube Video

[Bizill]

Yes. White flakes from an SWG are almost always scale. What else could the white flakes be?



Yes. Inside the SWG cell, when it is generating chlorine, the pH increases strongly due to the formation of hydroxide ions. The pH increase from the chlorine generation process will eventually be compensated for by all of the acidic chemical reactions caused by chlorine oxidation and disinfection, as well as the formation of hypochlorous acid from the dissolution of chlorine gas. But, in an instantaneous sense, the pH inside the cell is high. It can go as high as 10 to 11. This is why salt cells scale up - because the water that flows through them almost always has appreciable amounts of calcium and carbonates in it.



My suggestion was to simply use some diluted MA (20 Baume or 31.45%) to make the test safe to perform with fewer fumes. Full strength MA is not fun to play with outside of a fume hood.



It is possible to get all three scaling types if all three anions are present in the water (carbonate, sulfate and phosphate).




If you’d like to read a short, 2 page primer on the chemistry of calcium scale, this technical bulletin from Dow Chemical is interesting - Search

It’s not just the calcium ions that matter, it’s BOTH the concentration of the cation (calcium) and the concentration of the anion (carbonate, sulfate and/or phosphate) that matter. You need enough of both chemical species to exceed the solubility product of the resulting scale compound. So, if water has high CH, then one can keep the carbonate anion levels lower (as measured by TA) to compensate. In my pool I have had CH levels as high as 1500ppm but no scale...why? Because of I keep my TA at 50ppm (with a CYA of 90ppm and borates at 50ppm), then my carbonate level is so low that’s it doesn’t matter. But here’s another interesting fact - I have gotten sulfate scaling from my SWG cell...why? Because I had my pool tiles cleaned by kierserite blasting (kierserite is magnesium sulfate) and that added enough sulfate to my water to cause scaling (white flakes). The flakes, when tested against diluted MA, would not fizz but very slowly dissolve. If they were calcium carbonate scale, then they would have fizzed like crazy. So, as you can see, concentrations matter a lot.

It not usually hard to figure out why scaling occurs. In those pools that have scaling from the cell, even if the bulk pool water is “balanced” according to the LSI (or CSI, doesn’t really matter which you prefer), the water may not be balanced inside the cell. Thus, if the TA is a bit too high and the CH is on the high side, scaling is much more likely. Also, scaling is far more likely in a cell that is run at 100% or near that output than a cell that is run at lower output but for a longer period of the day. One way to compensate for pH rise inside the cell is to add borates to the pool water. Borates act as a high pH buffer and have their strongest buffer capacity as the pH nears 9. So, if enough borates are present, the pH of the water inside the cell won’t go much above 9.

I'm gonna have to really look further into this. Long time member here but have gotten lazy over the years. Now I have a SWG and get the flakes and have about 700 CH and have to clean my SWG cell every weekend.... First time the 30% vinegar to 70% water caused fizzing. Now it only seems to dissolve the flakes on the cell. I'm in Tucson as well.

 

[JoyfulNoise]

I'm gonna have to really look further into this. Long time member here but have gotten lazy over the years. Now I have a SWG and get the flakes and have about 700 CH and have to clean my SWG cell every weekend.... First time the 30% vinegar to 70% water caused fizzing. Now it only seems to dissolve the flakes on the cell. I'm in Tucson as well.

I added a whole house water softener back in 2018 to my home and hooked my auto fill up to it. Single best investment I made towards pool care as my CH barely budges. Many plumbers will tell you you can’t do that and you’ll wreck your water softener or the softener will run all the time … blah, blah, blah. Size the softener correctly and it works perfectly. Between that and adding borates to my pool water, I solved a lot of the typical Tucson pool problems.

I suggest you drain the pool in the fall and bring the CH down to fill water levels. High CH wrecks an SWG. You also need to keep your pool off hard water. If you don’t, you’re just going to march your SWG to an early death.

 

[Bizill]

I added a whole house water softener back in 2018 to my home and hooked my auto fill up to it. Single best investment I made towards pool care as my CH barely budges. Many plumbers will tell you you can’t do that and you’ll wreck your water softener or the softener will run all the time … blah, blah, blah. Size the softener correctly and it works perfectly. Between that and adding borates to my pool water, I solved a lot of the typical Tucson pool problems.

I suggest you drain the pool in the fall and bring the CH down to fill water levels. High CH wrecks an SWG. You also need to keep your pool off hard water. If you don’t, you’re just going to march your SWG to an early death.

Yeah, spent a couple days weeks researching SWG and only after the fact found that I may not be the best candidate. For me, I simply need to resurface my pool, but Crud, I don't have that kind of money... well, my priorities are fubar because I spend money elsewhere. So for the longest time I've tried to bandaid my issue but it's gotten worse over the past few years. It's my fault. And now I'm learning that my $1700 bandaid in the SWG is not being treated well. I just got to the point I was sick of watching bleach prices keep rising and didn't want to support the chemical manufacturers.

Had I learned in my few days of research that I might not want to go the SWG route, then I probably would have lost the pool to algae completely. But then I would have drained and started over. I've been on the verge of settling for a hole in the ground as many others but keep working around the true fix. Since I am here though, I get calcium buildup on the SWG cell to the point it's caked on within a week. I guess I should think about maybe half drain and refill as you suggest to get to tap water levels of CH. I don't use pucks and have used bleach for over 10 years now so I'm surprised that the CH has risen so high. Then again, I haven't checked the tap water CH levels in as long as I can remember. Probably never.

 

[JoyfulNoise]

Tucson has over 100” of evaporation per year. The municipal water here, on average, has 200ppm CH. That means most pools will increase in CH at a rate of 200-300ppm per year. Your actual CH may be a lot higher than what the test is showing because the test is really only good up to 800ppm CH. In order to practically test high CH water you have to use a sample that is diluted with distilled water first and then multiply the results by the dilution factor. Calcium hardness and scaling is a major problem here. There are no easy or cheap solutions.

 

[Bizill]

I joined many moons ago and started fresh with a drained pool and things have been fine (enough) for years so I had forgotten all that I learned when I joined and now throwing an SWG into the mix. Things seem so much harder now than originally, when it was only BBB. I need to get back into the groove of things. Gotta read up and re-educate myself and delve even deeper than before. Lowes sodium hyperchorite went from what, $7 for 2 gallons to last I bought a month ago was at like $19 now? My chlorine demand is worse now as well as I watch plaster chip away. Again, my fault. Didn't need that side by side, needed to redo the pool but we hit up Redington every weekend so money goes to that hobby.