Liquid Chlorine Only Question

[HammerGeek]

First off, I have read the "How to Chlorinate Your Pool" article in Pool School (BTW, I love Pool School).

What do you recommend for a pool that is not "my pool"? I service some pools (cleaning and chemical balance) and want to do this the best and most cost effective way. Liquid chlorine appears to be the best option. However, if I only service a pool once a week, it is horrible to use a few Trichlor sticks in the skimmer to maintain the chlorine level between servicing?

I'm trying to find an acceptable level of Trichlor use that doesn't add more CYA that the pool can use up. Pool School says, "The CYA that they put into your pool water doesn't get used up, and instead accumulates. Eventually the CYA level will build up to a point that renders your chlorine ineffective."

Is there a level of use of Trichlor that does get used up?
Is there a way to monitor this (Just watch CYA?)?
Is there another option besides adding liquid chlorine throughout the week as needed?

Thanks a bunch. I'm so glad I found this place.
And I love my new TF-100 kit. Just got it yesterday....and wow...my eyes have been opened.

 

[pabeader]

Unfortunately, TFPC doesn't work well with weekly maintainance plans. CYA goes away so slowly, like 1 ppm per month, that any regular use of pucks is unfeasable. Same is true for powders.
The only way you could make it work, is some type of automatic chlorine like a Stenner or SWG. You could also have the owner do daily checks and adds of liquid chlorine and you do a weekly reality check and adjust stuff like pH, along with the filter cleaning, leaf retrieval and basket emptying you do.

 

[mgmoore7]

Is there a level of use of Trichlor that does get used up?

CYA only gets used up with splash out.

Is there a way to monitor this (Just watch CYA?)?

You can use the CYA test in your TF-100 kit to monitor.

Is there another option besides adding liquid chlorine throughout the week as needed?

I have seen some services offer to install a Salt Water Chlorine Generator. That is really the only reasonable solution for a weekly service to try to follow the TFP way.

 

[tim5055]

Welcome to TFP!

As has been pointed out, weekly service does not lend itself to the practices taught here. Switching to a salt water chlorine generator or, slightly less expensive is a Stenner pump allows for consistant chlorine additions.

Now, dealing with individual questions/comments you have-

CYA/Stabilizer degrades very slowly. As Bob pointed out, 1ppm per month is a good number to use.

We NEVER recomend putting tabs in the skimmer. Tabs are extremely acidic and can damage the plastics that make up the skimmer housing. Additionally, when the pump,shuts off the puck,just sits there continuing to dissolve. When the pump turns back on this highly acidic water gets pulled through the system all at once, which over time can damage other parts like pump seals.

 

[Durk]

Well, you could dump the pool every six months and start over. I used pucks exclusively that way for twenty-five years successfully. It was only when I switched to a pool that didn't get dumped in the fall I had to convert to TFP.

 

[Kiss4aFrog]

You need a floater for the tablets. Putting them into the skimmers will make the baskets brittle and require more frequent replacement. It can also damage the pipe in the skimmers line and that can be brutal to repair.

 

[Chasmengr]

Alert -- Advice-from-newbie:

After my chemistry stabilized about 3 weeks ago, I found that I was adding a nearly consistent amount of chlorine every day. I now add that amount every day and test FC, CC, and pH about every three days doing other tests less often. (Perhaps do chemical balance twice a week and cleaning once a week?) Between your chemical visits, your owners could add a known quantity of chlorine everyday; you could pre-measure & pre-package it for them.

A pool is safe for swimming as long as FC ppm is below shock level. Difference between minimum and shock levels is significant, so you could pre-measure a bit high to stay safely above minimum.

I have a cartridge filter, so have no backwash losses, which helps a lot with predictability.

 

[mgmoore7]

One of the things to think about is that no matter what method of chlorination, without frequent testing of FC, you will need to run a higher FC to have a larger buffer to compensate for variations in FC demand.

For example, when a customer has a uncharacteristic high use of the pool over a weekend and it might happen to be hotter than normal. If there is not a enough buffer (or extra FC in the pool) for this over a whole week without a test, there would be a risk that the FC would get too low. Normal TFP method would be to test daily and just add more Chlorine/Bleach to compensate.

Remember, that TFP maintains that once the overnight test passes (OCLT), as long as FC is maintained higher than the minimum based on the chart, then the need to SHOCK / SLAM is eliminated.

I have been finding that even with a SWG, targeting a few FC higher than the Target value for my CYA is safer.

Pool School - Recommended Levels

Pool School - Perform the Overnight FC Loss Test (OCLT)

 

[HammerGeek]

Thanks everyone.

Some of your comments about "dumping the pool every six months and start over" are seeming real to me now. I'm one year in to owning my pool and my latest test using TF-100 says to replace half the water due to the CH and CYA readings. Sounds like I'm experiencing what you guys are talking about.

Is it bad to slowly pour liquid chlorine in the skimmer? At first I thought it would be a good idea because the pump would distribute it out the jets and I could also minimize splash by knelling down and pouring slowly.

Thanks again for you help.

 

[JoyfulNoise]

The only way service companies can make liquid chlorine work is by using a method called high CYA/chlorine (HC²). Basically you would raise the CYA into a range of 100-150ppm and then adjust chlorine at 10-15% of CYA when you dose weekly. The idea is that you add a large amount of chlorine upfront to kill anything and everything in the water and then *hope* that the CYA can hold the daily loss rates down to a low enough level so that, when you return a week later, you're still treading water . Typically you would also use a supplemental/secondary sanitizer such as borates to 50ppm and/or polyquat-60 algaecide. It would be best to add the Polyquat a few days after the mega-dose of chlorine to avoid oxidation of the Polyquat but even oxidized polyquat still has algaestatic properties. The downside to the method is, if you do develop algae, you will need a tanker-truck of Clorox to get the FC high enough to shock the pool. In those cases, pool service companies will use an acid/shock/floc method to clear the water - drop the pH below 7.0 with a large dose of acid, add a TON of chlorine to shock the snot out of the water and then floc the pool. They will then return the next day to vacuum the debris to waste.

None of those are methods of pool care that TFP would ever suggest anyone to use on their own pools for obvious reasons of cost and harshness, but it can work in a pool service environment if you take care of pools owned by people who don't want to take care of their own pools.