Yet another question about CYA/FC relationship.

[Mark McLeroy]

Ok. first let me start by saying I am a 100% believer in the TFP method of balancing water. I do all my own testing, and it is VERY rare that I walk into a pool store (I have to be desperate for something). However, I find that I am tempted to stray from one TFP recommendation on water balancing. I have a SWG (see signature for equipment and testing supplies). I do no like putting unnecessary chemicals in my pool. Here are todays testing results.
FC = 5.5
CC = 0.0
PH = 7.8
TA = 80
CA = 180
CYA = 40 *
Water is TFP Clear.

As you can see my CYA is lower than TFP suggest for SWGs. However, I find that if I keep my SWG on 40% on hot, sunny days it has Absolutely no problem keeping up with Chlorine demand. In fact, at night, I have to lower the SWG to 15% or 20% to keep the FC from going above recommended levels (heck sometimes I turn it off). I run my pump 24 hours a day.
My question is, under the circumstances, is it still recommended to raise the CYA to a minimum of 60 PPM? I have a fiberglass pool, draining is problematic, and I want to keep the total dissolved solids down.
Thanks..

 

[Donldson]

Why are we worried about TDS? You have a salt pool with thousands of ppm of dissolved salt, 20 ppm of CYA is a rounding error in your TDS.

 

[Newdude]

My question is, under the circumstances, is it still recommended to raise the CYA to a minimum of 60 PPM?

Nope. You are doing *exactly* as you should. Become one with your pool and respond to how it behaves.

If you find a lower CYA isn't keeping up down the road in a brutal heat stretch, raise it by 10 and road test that. It's wise to Overnight Chlorine Loss Test before raising the CYA though, so prove there's no algae first if the need ever arises.

 

[Mark McLeroy]

Why are we worried about TDS? You have a salt pool with thousands of ppm of dissolved salt, 20 ppm of CYA is a rounding error in your TDS.

When you put it that way it does seem insignificant. I just dislike adding anything that's not necessary (especially if it would require a problematic solution to fix).

 

[Mark McLeroy]

Nope. You are doing *exactly* as you should. Become one with your pool and respond to how it behaves.

If you find a lower CYA isn't keeping up down the road in a brutal heat stretch, raise it by 10 and road test that. It's wise to Overnight Chlorine Loss Test before raising the CYA though, so prove there's no algae first if the need ever arises.

I like your thinking Newdude. If it ain't broke, don't fix it.

 

[Newdude]

When you put it that way it does seem insignificant.

To expand on Donldson's point above, TDS is a junk stat. (Along with TC). Here's my layperson reason why.

You have 37 things in your fridge. Do you need to grocery shop for dinners this week, or is 37 things enough ? No freaking clue, right ?

It's because 37 things tells you nothing. It could be 37 condiments on the fridge door, or 2 lbs of chicken, 6 lbs of various beef and lots of things to make side dishes.

So the components of TDS all matter by themselves. Keep them in the range that works best for you. The sum of the components means bupkiss.


*just checked and had 43 items on the fridge door.

 

[Saturn94]

As long as you’re able to maintain proper FC levels, then it’s up to you what you do. The TFP police won’t come knocking at your door.

Adding CYA would likely reduce your daily FC loss, thereby demanding less of your SWCG and prolonging cell life.

Personally, I like to minimize FC loss to maximize cell life, especially considering cells now cost more than double than they did just a few years ago, so I keep CYA 70-80. At 60 or below, I do notice an increase in daily FC loss.

 

[Saturn94]

To expand on Donldson's point above, TDS is a junk stat. (Along with TC). Here's my layperson reason why.

You have 37 things in your fridge. Do you need to grocery shop for dinners this week, or is 37 things enough ? No freaking clue, right ?

It's because 37 things tells you nothing. It could be 37 condiments on the fridge door, or 2 lbs of chicken, 6 lbs of various beef and lots of things to make side dishes.

So the components of TDS all matter by themselves. Keep them in the range that works best for you. The sum of the components means bupkiss.


*just checked and had 43 items on the fridge door.

I hate grocery shopping! I’d figure out some kind of meal with those 37 items.