Why are TFP's recommended levels so different than my equipment manufacturer's?

[aprillh]

Most concerning is FC. TFP recommends 4-6, Hayward 1-3. Pretty big difference.

CYA 70-80, Hayward 30-50
TA 60-80, Hayward 80-120
pH 7.5-7.6, Hayward 7.2-7.6 not that much different but Hayward has a wider range.

I've been trying maintain my pool with TFP's recommendations but I can't figure out why they want FC so much higher. Thoughts?

 

[jblizzle]

The FC differences are because the pool industry does not seem to acknowledge the CYA/FC relationship.
The higher TA is needed if you use acidic forms of chlorine, like trichlor tablets which we do not recommend.
pH just needs to be in the 7s.

 

[Patrick_B]

FC

Because the EPA does not recognize the Cya/FC relationship, and these are their guidelines for pools. Manufacturers will/can not go outside that.

CYA

Higher here for Salt Pools, because it keeps the SWG from working harder (extra) to make more FC. High Cya gives more protection keeping losses of FC minimal, therefore the SWG doesn't have to make up extra for those losses.

pH

Because it's easier to maintain and less fight to push it down to 7.2 all the time. It also helps a little in keeping folks from going down too low on dosing. There are instances (lowering TA) where we do suggest pushing it down to 7.2. That said, 7.2-7.8 is a great range for most situations.

 

[elwood58]

I will chime in as well. Higher CYA allows for a much lower duty cycle on the salt cell. Makes the cell last longer, and saves money on Power too. SWG is creating a micro shock environment within the cell, which also reduces the chance of algae, providing you have enough run time to turn the pool over a few times a day.

The lower TA seems to help buffer pH rise, which is a fact of life with an SWG due to aeration.

pH tighter range keeps most people out of trouble with overall balance, reducing the instances of scaling or etching that can occur when getting too high or too low.

 

[remotedoug]

As a new pool owner myself, I questioned the same thing. From all of my reading in these forums (excellent information), I came to the conclusion that I needed to balance the numbers from the TFP method with the manufacturer's specs. I took all of the ranges and found where they crossed over, then set my own targets in the middle. It may not be perfect, but so far I have a sparkly pool and am within my warranty guidelines.

Here is the chart I keep in my test kit:

TFP Pentair Crossover Target
FC 4.0-6.0 2.0-4.0 4 4
PH 7.5-7.8 7.2-7.8 7.5-7.8 7.6
TA 60-80 80-120 80 80
CH 250-350 200-400 250-350 300
CYA 70-80 50-80 70-80 75
Salt 3600-3800 3000-4500 3600-3800 3700

 

[chem geek]

At least for CYA, SWG manufacturers vary in their recommendations with quite a few recommending 60-80 saying 70-80 is "ideal". See Hayward AquaRite which says "60 to 80 ppm (80 ppm best)". See AutoPilot PoolPilot Digital which says "60 to 80 ppm" for most pools. See Pentair IntelliChlor which says "75 ppm".

Unfortunately, most of these manufacturers say not to use any CYA at all in indoor pools, but at the higher end of their FC recommendations with no CYA in the water the chlorine will be very, very strong oxidizing swimsuits, skin, and hair at 10-30 times the rate of their outdoor recommendations. They don't have any understanding whatsoever of the chlorine/CYA relationship in terms of the chemistry.

So which Hayward model are you looking at that says 30-50 ppm CYA?

It's only FC where you won't find anyone recommending anything higher than 4 ppm due to EPA drinking water limits (such limits not having any CYA in the water).

 

[Divin Dave]

I agree with what everyone else says.

 

[kris77]

When you say Haward 30-50. I keep my CYA at 40, so that is spot on for me.

Same with TA. I run from 80-110. 90 is my target. 7.5 if target PH. So everything but FC adds up for me on both fronts....TFP and Manufacture Specs. But I dont have a SWG.