Good morning all. Seems like I'm constantly fighting to keep my pH in the desired 7.4-7.6 range and alk 80-120 in my 15,000 gal, pebble tech pool. You guys already know this....adding muriatic reduces pH but it also reduces the alk. Adding baking soda raises the alk but also raises my pH. Just can't seem to find the sweet spot.....tough to keep them both in range without spending a fortune. In order to keep the sat index acceptable and not go broke I've been simply keeping pH at 7.9-8 and alk at 50-60. A lot less chemical needed to maintain pH and alk at these levels and still keep sat index somewhat acceptable. Is it okay to run pH high and alk low like this? If not, any thoughts on why I'm having to use 2-3 gallons muriatic and 4 lb baking soda per week to keep pH and alk close to recommended levels? More info - I'm using trichlor tabs (one 3"/week) with a splash of liq Cl each week. Hardness naturally rides at 325. CYA about 40. Freshwater pool. Water is crystal clear!!! Thanks in advance for thoughts and suggestions.
Chasing pH
- Thread starter Jim Nelson
- Start date
-
- Tags
- alkalinity chlorine ph control
- Jun 24, 2021
- 16,079
- Pool Size
- 29000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
It’s because those recommended levels are close to impossible to maintain long term, and each one tends to counteract the other and makes it easy for the pool store to have a steady stream of income.
Doing exactly what you did is what TFP recommends. The TA recommendation can work ok when you are using trichlor tablets for chlorination, but they tend to lower the TA and pH.
- Jul 17, 2019
- 4,071
- Pool Size
- 13000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
I've seen people drive themselves crazy trying to micromanage their pH and keep it in the mid-7's (and usually at the expense of taking care of more important numbers like FC). Good job Jim finding that sweet spot. My pH loves to hang out in 7.8-8.0 as well. When I do have to add acid I target 7.4, and it will quickly jump back up to 7.8 but then hang out there for weeks until I need to add acid again.
Maybe (hopefully) I can save you a little more time & effort. First, I’d stop using the tabs — sooner or later your CYA rise will make you have to exchange some water. Per the TFP advice, when pH hits 8, add acid to lower it to the point where CSI hits -0.6 (which for my water is around pH 7.4). Let it rise naturally without having to do anything. When it hits 8 again, add acid again, etc. What will happen over time is TA is reduced to a level (around 50 ppm) where pH won’t quite get to 8 anymore (unless high TA water has to be added). Keep CH where the pH just below 8 result in a CSI within range (I got the SWG, so I keep CSI within the negative end of the range). That’s it.
At first, acid additions may be frequent but after a while pH rise slows enough that having to do anything becomes very infrequent or even never if rain offsets evaporation. For my pool, after about the first month or so of the season, pH tends to stabilize just below 8 and I don’t need to do much else. A pool is supposed to be fun so I try everything I can to make it as little of a headache as possible. Luckily I live where needing to add water is very infrequent.
At first, acid additions may be frequent but after a while pH rise slows enough that having to do anything becomes very infrequent or even never if rain offsets evaporation. For my pool, after about the first month or so of the season, pH tends to stabilize just below 8 and I don’t need to do much else. A pool is supposed to be fun so I try everything I can to make it as little of a headache as possible. Luckily I live where needing to add water is very infrequent.