Check Valve Behind Salt Cell

[AFiremanFirst]

Okay guys. I have 20 pool contracts that I clean weekly. I have an opionion, then I get a different answer from my local builder (a friend) supported by plumbing done by other builders in my area. Humor me. A chlorine tower, or rainbow auto chlor (9-10 tablet tower with a dial, in-line with pressure side) reccommends a non-corrosive check valve to prevent super chlorinated water from washing back to the heater and predisposing it to corrosion. With that said. I had a customer lose a heater in 7 yrs. It's a salt cell pool with the generator after the heater. I'm thinking avg heater life is 15 yrs. There is no check valve behind the salt cell. I stand to reason that when the system shuts down, the generator is at desired setting and generating desired chlorine ie 65% or whatever. In other words. The cell doesn't shut down, the pump flush fresh water, and then the pump shut down. I reason this as the controllers are standard intermatic clock switches, one for the pool one for the cleaner, and the salt cell generator is completely seperate from knowing when to turn off. So it turns off the second the pump turns off. In my head this means the cell is generating chlorine that potentially backs up into the heater and can cause corrosion. So... shouldn't there be a check valve. Isn't it fair to reason that at even 25% we're talking about high levels of chlorine potentially backing up into the plumbing and heater. I'll add that if there were no heater I'd be less concerned.

Thanks for all your help.

[Pool Clown]

Almost all Cl generators say that you should put a check valve in. Having said this, there are a few things that don't really warrant a check valve, but the manufacturer(s) say to install one (just to be safe) and it covers them. If your generator is wired correctly, the unit shuts off when the pump does, chlorine prodution stops and there isn't any more chlorine migrating from the cell, unlike an erosion feeder that never stops dissolving Cl. Also, your percent adjustment controls the amount of time that the unit runs, not the amount that is produced.

[polyvue]

Almost all Cl generators say that you should put a check valve in. Having said this, there are a few things that don't really warrant a check valve, but the manufacturer(s) say to install one (just to be safe) and it covers them. If your generator is wired correctly, the unit shuts off when the pump does, chlorine prodution stops and there isn't any more chlorine migrating from the cell, unlike an erosion feeder that never stops dissolving Cl. Also, your percent adjustment controls the amount of time that the unit runs, not the amount that is produced.

I don't have a check valve prior to my Goldline Aqua Cell but there is a 5 foot straight run between the heater and the cell. I think Goldline mentions this in their installation manual. That probably mitigates any chemical backup, however slight, back to the heater following shut-off.

[txpoolguy]

Goldline does not require a check valve between the heater & cell. The amount of chlorine being generated isn't normally enough to cause problems with the heater. The flow switch stops production of chlorine when the water stops moving. It's very likely that what you're seeing is coincidental. Having said that, heater mfgrs recommend a check valve between the heater & chemical feeder, however they don't consider the electronic generators to be the same as a tablet feeder. If you have a concern, it is simple to add one, but be sure to add one that is chemical reisistant. I've seen many cases of heaters damaged by chlorine from tablet feeders because the check valve wasn't chemical resistant.

[AFiremanFirst]

All good information! Thank ya'll very much. I didn't realize the percentage was a time however??? How would that work? My intermatic timers and my salt cell generator are in no way connected, 2 completely different, independent systems. I've put in several of these "non-corrosive" valves, when people don't want to spend the money for a new cell, but was just curious about the back of chlorine in generators. Coincidence sounds like a good answer, for my house however I think I'll make the $15.00 insurance investment. Thanks again.

[txpoolguy]

The percentage of output is actually the percentage of runtime in a 2 hour cycle. This is built into the AquaRite. So, 50% output is ON for 1 hour, OFF for one hour. 75% output is ON for 90 minutes, OFF for 30 minutes, etc. In a 7 hour filter cycle, "3-2hour cycles, plus one hour, the last hour will be ON and the pump will turn off. Superchlorinate is the same as 100% output.

[Pool Clown]

The percentage of output is actually the percentage of runtime in a 2 hour cycle. This is built into the AquaRite. So, 50% output is ON for 1 hour, OFF for one hour. 75% output is ON for 90 minutes, OFF for 30 minutes, etc. In a 7 hour filter cycle, "3-2hour cycles, plus one hour, the last hour will be ON and the pump will turn off. Superchlorinate is the same as 100% output.

The length of Cycles are manufacturer specific. Example: The Aqua-Rite is two hours, the Aqua-Pure is three. The best thing to do is read the manual of the unit, to get the actual cycle time of your particular generator.

[AFiremanFirst]

again! Good information! I'll look up the manual. it's a goldline t-15 if memory serves me correctly.

[AFiremanFirst]

well... it wasn't that easy. My controller says goldline. my cell only says "turbo cell" t-15, no manufacture. any help? One other question. I've always used a 2 parts water to 1 part acid for cleaning the cell. In line with what I did find concerning this cell. however they recommend 3-4" of water and 1-1.5" of acid, soak one end, then the other. Doesn't seem like a deep enough mix of solution to cover all of the cell. I've always used a gallon of acid and 2 gallons of water, or enough water to submerge my cell. Is this not recommended for a reason I can "reason"?

[polyvue]

well... it wasn't that easy. My controller says goldline. my cell only says "turbo cell" t-15, no manufacture. any help? One other question. I've always used a 2 parts water to 1 part acid for cleaning the cell. In line with what I did find concerning this cell. however they recommend 3-4" of water and 1-1.5" of acid, soak one end, then the other. Doesn't seem like a deep enough mix of solution to cover all of the cell. I've always used a gallon of acid and 2 gallons of water, or enough water to submerge my cell. Is this not recommended for a reason I can "reason"?

If your controller is Goldline doesn't that indicate that you have a Goldline cell? Or are you saying this is an aftermarket product (didn't know there were any)? I've seen a bunch of synonyms for the cell I have (Hayward Goldine Aqua Logic PS-8 controller with Aqua T-CELL-15) including "Turbo Cell" "Aqua Rite" and others.

Here's the manual for the standalone SWG (Aqua Rite controller and cell) [PDF file]

Cell maintenance is discussed beginning on page 38 in the PS-8 operation manual (Aqua Logic PS-8 controller & cell) [PDF file]

[Pool Clown]

How would that work? My intermatic timers and my salt cell generator are in no way connected, 2 completely different, independent systems.

I would fix that, just to be on the safe side. Your Generator should get its power from the time clock load side, not directly from the breaker. That way when the pump turns off, so will the generator. This would safeguard against a sticking /failed flow switch.

[txpoolguy]

There are a variety of "knock-off" cells becoming available. I would guess that the TurboCell T-Cell-15 is likely a Goldline product. All brands are proprietary, so a Jandy cell will not fit a Goldline control box, vice versa. 20-25% solution is generally recommended for cell cleaning 1 part acid to 3 or 4 parts water. Submerge cell until it quits bubbling inside, or a maximum of 15 minutes per treatment, treat multiple times if necessary. As the acid is removing the scale, it's also working on the metal plates, so be gentle.