- Jan 4, 2016
- 5,390
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
I would do the borates because your scale issue is perplexing and I'm interested to find out if it helps. It won't hurt the plaster so all good there. If leaving your TA high, delay your CH increase until it's needed to balance CSI.
Ignore the rest of what I say...
A lot of people would say don't worry about lowering the TA anyway. Most of what lowering it will do is spread out the frequency of acid additions. If you're away a lot, that can be important. There are some writings that say lower TA reduces the amount of acid needed to counteract the pH rise from an SWG, but I haven't read anything yet that convinces me. On the other hand, I could believe it because some of what goes on in the guts of an SWG cell housing is poorly understood.
If you want to spread out the frequency, you can go lower when you lower your pH, to 7.2 for example. This will cause slightly higher acid consumption, so it's a convenience vs. cost thing. It won't be a huge amount more acid. I've seen some chem equations that suggest to me that in the long run, it isn't any more at all. It's just X TA in = Y MA to counteract it. But it's not within my grasp yet.
It makes sense though, because why would taking your pH lower once a week be any different from the TA lowering method? It's just on a slower cycle time because of slower aeration.
If you want to reduce cost, lowering TA aggressively may just cost a bunch of electricity for aeration. It will happen on it's own from the in-range acid additions. (and some from rainfall as pooldv mentioned, which is free!).
If you want to fit the recommended ranges sooner rather than later, you'll notice a "+" after the 90 in the recommended ranges. So to me it's like it is for the high CH people. They go above the recommended CH number, and adjust TA and/or pH to keep their CSI where they want it. People with high TA water can successfully run their pools at high TA by reducing CH and/or pH to keep their CSI where they want it.
On new plaster, I think near 0 or slightly negative is good. For you with a weird scale issue, a bit more negative (-0.2) is probably better, but hey, we're talking tiny differences and we're in ghostbuster land anyway, right?
Ignore the rest of what I say...
A lot of people would say don't worry about lowering the TA anyway. Most of what lowering it will do is spread out the frequency of acid additions. If you're away a lot, that can be important. There are some writings that say lower TA reduces the amount of acid needed to counteract the pH rise from an SWG, but I haven't read anything yet that convinces me. On the other hand, I could believe it because some of what goes on in the guts of an SWG cell housing is poorly understood.
If you want to spread out the frequency, you can go lower when you lower your pH, to 7.2 for example. This will cause slightly higher acid consumption, so it's a convenience vs. cost thing. It won't be a huge amount more acid. I've seen some chem equations that suggest to me that in the long run, it isn't any more at all. It's just X TA in = Y MA to counteract it. But it's not within my grasp yet.
It makes sense though, because why would taking your pH lower once a week be any different from the TA lowering method? It's just on a slower cycle time because of slower aeration.
If you want to reduce cost, lowering TA aggressively may just cost a bunch of electricity for aeration. It will happen on it's own from the in-range acid additions. (and some from rainfall as pooldv mentioned, which is free!).
If you want to fit the recommended ranges sooner rather than later, you'll notice a "+" after the 90 in the recommended ranges. So to me it's like it is for the high CH people. They go above the recommended CH number, and adjust TA and/or pH to keep their CSI where they want it. People with high TA water can successfully run their pools at high TA by reducing CH and/or pH to keep their CSI where they want it.
On new plaster, I think near 0 or slightly negative is good. For you with a weird scale issue, a bit more negative (-0.2) is probably better, but hey, we're talking tiny differences and we're in ghostbuster land anyway, right?