Help with high CH

[spoonman]

Hello! I've read a number of threads on controlling CSI but can't quite pin down the best strategy for my pool.

I'm in Phoenix with a CH of 700. The fill water here is very high in CH, so RO is the only option for my pool besides controlling the issue with proper chemistry. FWIW, I chlorinate manually with liquid chlorine, never cal hypo.

Here are my numbers:

CH 700
TA 70
PH 7.3 at the moment, but has significant drift (9 month old plaster pool)
Temp ~83

According to the Taylor Watergram calculator, I need to keep a pH of 7.1-7.2 to maintain neutral water at these metrics. Especially with my pH drift, it is very difficult to maintain this small pH range which also seems quite low.

Should I be lowering TA more or focusing on keeping a very low pH?

Thanks

 

[JoyfulNoise]

Stop using the Taylor Watergram, it's based on the LSI. Use PoolMath and focus on CSI value. All you need to do is keep the CSI between -0.3 and +0.3 and you'll be fine.

My water has a CH of 1150ppm and I can manage it just fine with a pH at 7.6. No need to go down to 7.1-7.2 as you'll never be able to maintain a pH that low.

Forget about RO treatments, they're typically worthless. The equipment most pool-based RO providers use is mickey-mouse toys that can't generate enough pressure to properly operate an RO filter. Because of that, the waste water fraction is very high (20-25%) which means that you'll be filling up the pool with a lot of water from your spigot while their RO filter is running. It's typically much cheaper to simply drain the pool and refill it.

 

[BuckeyeChris]

Stop using the Taylor Watergram, it's based on the LSI. Use PoolMath and focus on CSI value. All you need to do is keep the CSI between -0.3 and +0.3 and you'll be fine.

My water has a CH of 1150ppm and I can manage it just fine with a pH at 7.6. No need to go down to 7.1-7.2 as you'll never be able to maintain a pH that low.

Forget about RO treatments, they're typically worthless. The equipment most pool-based RO providers use is mickey-mouse toys that can't generate enough pressure to properly operate an RO filter. Because of that, the waste water fraction is very high (20-25%) which means that you'll be filling up the pool with a lot of water from your spigot while their RO filter is running. It's typically much cheaper to simply drain the pool and refill it.

I can vouch, I had mobile RO run on my pool, and it took 4 days I think to get the CH down to 200. With the amount of waste water...I would have been better off just draing 3/4 of the pool. HOWEVER, my fill line is on a softerner. If you drain and refill with just tap water, doesn't really help you out much since the fill is also high CH.

Keep adding acid, you'll get the TA down to 40 or 45, and that will help your CSI. Also, keep using liquid chlorine and your salt level will go up, which will also help your CSI.

 

[JoyfulNoise]

I can vouch, I had mobile RO run on my pool, and it took 4 days I think to get the CH down to 200. With the amount of waste water...I would have been better off just draing 3/4 of the pool. HOWEVER, my fill line is on a softerner. If you drain and refill with just tap water, doesn't really help you out much since the fill is also high CH.

Keep adding acid, you'll get the TA down to 40 or 45, and that will help your CSI. Also, keep using liquid chlorine and your salt level will go up, which will also help your CSI.

Your experience is the one I always have in mind whenever people mention RO.

I will say this - my municipal water typically has a CH of 250-300ppm. So, with a 100% drain and refill, that starts me off in the exact sweet spot for CH. Unfortunately, with just regular tap water plumbed in my fill line, I'm not doing myself any favors long term.

 

[spoonman]

Thanks guys got the help. It sounds like based on Pool Math, I can control the CSI by keeping a pH between 7.2/3 - 7.5/6. This based on TA of 70 and my CH and temp conditions. Admittedly this still can be a challenging window to hit since I have pretty high pH creep. Any ideas on how to make this pH easier to hold? Lower TA below 70? Look into Borates?

Edit: Buckeyechris just reread your post to power TA down to 40-50. Any more advice on this would be helpful.

 

[JoyfulNoise]

Thanks guys got the help. It sounds like based on Pool Math, I can control the CSI by keeping a pH between 7.2/3 - 7.5/6. This based on TA of 70 and my CH and temp conditions. Admittedly this still can be a challenging window to hit since I have pretty high pH creep. Any ideas on how to make this pH easier to hold? Lower TA below 70? Look into Borates?

You don't want to hold water pH in that range (7.2-7.5) as carbon dioxide outgassing (the chief driver of rising pH) is very fast in that range. You'd be better off dropping your TA another 10ppm and then managing your pH in the 7.6-7.8 range (only add acid once the pH goes above 7.8 and then only enough acid to drop it back down to 7.6). Do that should lessen the acid demand.

Try that before adding borates.

 

[spoonman]

Thanks Joyful. I'm in the process of getting my TA to 60 to reduce acid demand and pH rise. Sounds like that should help me stay inside the correct CSI range.