chlorine rise across chlorinator

Apr 26, 2014
12
Oak Grove, MO
Curious to know if my test results are normal. I have a 15k gallon above ground pool, using a Pentair 320. I have about 7 tablets in the chamber and it is wide open on 5. I have a 1.5hp pump, two speed, and it normally runs on HI.

Testing the water from the opposite end of the pool, I have a chlorine level of 5. If I test it directly from the return jet, chlorine is around 6. Just wondering if this seems normal? I expected the return jet to be higher since the Pentair is running on max. Was really thinking I'd have to turn the dial down a bit. What kind of increase would you expect across an autochlor wide open with fresh tablets? Just curious.
 
:wave: Welcome to TFP!!!

Wow, so many thing to discuss just from that first sentence, but I have to run and will come back to see what others said.

Please add your pool details to your signature and location to your profile as described HERE as it will help us help you.
 
No one? Well, you may not get too much feedback since a vast majority of the members do not use trichlor tablet feeders due to the negative side-effects (skyrocketing CYA levels and plummeting pH and TA levels) ... are you aware of these?

Based on what I have read about the FC jump across SWG ... I would think that a 1ppm rise across your chlorinator is probably reasonable.

FYI, using PoolMath, in your 15k pool each 8oz trichlor tablet will add 3.7ppm of FC and 2.2ppm of CYA nd lower your pH by 0.2
So, when those 7 tablets are gone, that will have added ~15ppm of CYA. Our recommended level of CYA is 30-50ppm so very quickly you will enter that range and shoot out the other side. You also need to realize that the required FC to prevent algae climbs as a function of CYA. See the FC/CYA Chart

Out of curiosity, why do you run the pump on high so much? That may just be a waste of electricity.

How much Pool School have you read? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool
 
Yes, I am aware of CYA. I decided to switch to bleach the end of last season and wanted to put in something to automate the bleach this year. Looked at Liquidator but did not want to inject in front of pump. Looked at Stenner, but then we went back to a single income and can;t afford it right now. I don't have time to build one from scratch and I still have a bucket of Trichlor tabs from last year so I'll have to make due with tablets and bleach. I really just plan on the tablets for a low dose maintenance. I was just curious about the chlorine rise across the device when wide open. Seemed low but I have no basis for that opinion.

My pump is a two speed. The LOW speed doesn't seem to have enough draw to effectively skim the surface so I run it on HIGH. Since it is on HIGH, i run it less that if I ran it on LOW. But again, these are assumptions without a lot of data. Originally I calculated the pump needed to run 6-8 hours per day...but it's been a while so I probably need to review my numbers/logic.

Thanks for the info!
 
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Do you have a weir on your skimmer? Do you have a floor drain that can be turned down for more skimming? With a 1.5HP pump I am surprised that low does not give you enough flow.

Some info on pump run time: http://www.troublefreepool.com/content/152-determine-pump-run-time

I understand your monetary concerns, but I would urge you to invest in one of the Recommended Test Kits. With that information, it will allow you to keep the pool clear which is MUCH cheaper than dealing with algae blooms. Also, the tablets will save for years, so you can use them when out of town or something. And using just bleach (once your CYA is in range), is usually the cheapest method of adding chlorine to your pool.

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PLEASE!!! for your own sanity and wallet ... do NOT trust the pool store testing. It is proven over and over again to be inaccurate and inconsistent. And you will always have to deal with the high pressure sales for $100s of chemicals.

Get a good test kit, keep reading here, and ask questions often. Following our methods you should be able to spend under $50 / month maintaining the pool.

Hopefully if you keep reading the forum and other people's thread you will realize that this is the best way to go.
 
Thanks for all the good info. I'm going to look at running the pump less....maybe on low. I do have a weir on the skimmer, but currently it is not installed. No floor drain. Thanks for the warning about the pool store tests....they seem so professional with printouts and graphs. Honestly, one of my biggest battles is getting my wife on board the BBB method. It is not what the "experts" do....not what her sister does with her pool (she pays someone to maintain it) and it is not what our neighbor (who works at a pool store) is telling us to do. Uphill battle.
 
It can be tough to convince people ... just ask for a few months to do it our way to prove it works and is cheaper.

The weir will make a HUGE difference in the skimming action ... it is a must.
 

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It can be tough to convince people ... just ask for a few months to do it our way to prove it works and is cheaper.

The weir will make a HUGE difference in the skimming action ... it is a must.
Ditto what he said.

Order the test kit and say it's your Father's Day present early. Then ask her to let you do it your way. And if it doesn't look great and get compliments when you host the Fourth of July Pool Party, you'll do what she wants. Seeing is believing.
 
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