SWG vs. BBB for High CH Water

[Howren73]

Unfortunately, i live in a region with hard water. my tap water has a CH of 400. sourcing fresh water that isn't hard is not possible, and plumbing my water softener to the auto-fill is not ideal.

we are currently in the process of building our pool, with just a couple more days left in the build. we originally told the PB we wanted saltwater, and he wasn't planning on even installing the SWG for a month so the plaster can cure. in the meantime it will be a standard chlorine pool.

so i'm curious which method will be easier to maintain, less expensive over time, and just plain better than the other for hard water?

 

[chiefwej]

SWG, no question!

I live in Tucson with high CH levels and very high evaporation rates. I have to keep a close eye on my pH level as it seems to also slowly rise, but no lugging bleach or tabs with their CYA issues. Just set the dial to adjust your chlorine level. I have successfully managed the pool with CH levels as high as 1,000 and no scaling.

 

[Howren73]

SWG, no question!

I live in Tucson with high CH levels and very high evaporation rates. I have to keep a close eye on my pH level as it seems to also slowly rise, but no lugging bleach or tabs with their CYA issues. Just set the dial to adjust your chlorine level. I have successfully managed the pool with CH levels as high as 1,000 and no scaling.

that's good to here, but contradicts your response to my other thread about sealing limestone rocks along our spillway.

 

[chiefwej]

Two seperate questions. SWG is great maintaining chemical balance, but does tend to damage natural stone surfaces. For that reason my pool has no stone anywhere. My deck is concrete with a textured acrylic finish, it has a cantilever edge, so there is no coping. Add waterline tile and pebbletec interior, means all surfaces are impervious to salt damage. Long term, any stone that comes in contact with saltwater will be damaged.

I suppose sealing the stone will help slow the process, but I choose to just avoid it completely.

 

[duraleigh]

so i'm curious which method will be easier to maintain, less expensive over time, and just plain better than the other for hard water?

You purchase an SWG for convenience, not cost savings. Not sure what you mean by "easier to maintain"......manual chlorination and SWG's are both easy if you understand them, but both require some maintenance.

Neither method of chlorine delivery, manual or SWG, has any effect on your CH issue.....that issue can only be corrected with your softener.

 

[Howren73]

i was at the local Leslie's getting some cleaning equipment and CYA and i told them i was doing SWG. of course they told me they didn't recommend it for our area because of the hard water. the pool boy said they are harder to maintain with hard water and i'll have to watch my TA closely. is he just blowing smoke up my rear trying to get me to give him all my money?

i'm still contemplating on whether or not to do the SWG system or just stick to BBB like i'm going to be doing for the next month as the plaster cures.

 

[chem geek]

He is right that with high CH water you need to watch your pH and TA more closely when you have an SWG to prevent scaling in the cell, but using 50 ppm Borates also helps reduce the amount of pH rise and scaling in the cell. If you want to have a saturation index of -0.2 to help reduce scaling in the cell, then the following combinations of pH and TA would work with a CH of 1000 ppm which is pretty darn high:

pH 7.3, TA 68 ppm
pH 7.5, TA 58 ppm
pH 7.7, TA 54 ppm

So yes, with a very high CH you could be aggressive with having the TA be low and often with high CH fill water it is also high in TA.

Now you are in Midland, TX where the 2011 Water Quality Report unfortunately does not show the water hardness level. This old report of well water shows 768 total hardness, but calcium hardness is 153*100.0868/40.078 = 382 ppm so not that bad (except for continual evaporation and refill which will increase CH over time) while TA is 244*105.9885/61.0168/2 = 212 ppm which is high. You should test your tap water with your test kit to be sure. You indicated your CH was 400 ppm, but didn't indicate your TA. At any rate, with your plaster curing and probably frequent pH rise, you can wait until that settles down before you make a decision.

 

[Howren73]

I believe the TA was either 0 or 10, solution was pink from the start. pH was 6.8-7.0. FC last night was 1 and rising as the trichlor tabs have not all completely dissolved. All the PB has added to the pool is 4 gallons of muriatic acid for the plaster curing, and then a couple days later he added a few trichlor tabs after plaster dust was cleaned up. I was going to wait until Monday to retest everything to give the tabs time to level out the CYA. I ordered the speed stir which should be in by then.

PB said all I need to do is add 1 or 2 tabs a week and the only time I should have a problem is when the chlorine burns my skin. I know better than that

 

[chem geek]

If the TA was pink or red from the start, then that means the pH is 4.5 or lower so this sounds like an acid startup for the pool plaster. After he stops adding acid (sounds like that may be the case now) and he tells you to start maintaining the pH normally near 7.5, you can then test again. Also, test your fill water itself -- the TA in the pool will be unusually low because the acid start will have driven off nearly all the carbonates in the pool. I suspect the TA in your fill water will be somewhat high given the high CH.

 

[Howren73]

That makes sense. I don't think the PB was planning on coming back to add chemicals. So with him adding 4 gallons of muriatic acid to the 12,000 gallons, what do I add to even it out? The acid was added this past Monday.

Tap water has a TA=170 and pH=7.6

 

[chem geek]

You should follow the instructions he has given you or ask him what to do because you don't want to violate any warranty he may have for the plaster job.