AG auto. Chlorine feeder

[SCpool]

Happy Spring everybody, I am a happy pool owner in SC with a 20,000 gal round AG pool. I started using the BBB method last year after a friend told me about the Pool Solutions website, but just joining the forum now. I wanted to ask about recommendations on an automatic chlorine feeder, if people use them successfully. Do you guys use them with the trichlor pucks?

We also just replaced our liner and so I'll be adding BBB when it's done filling up. Should I add CYA before I put in BBB since the CYA will lower the pH? It takes forever to dissolve. I put it in a sock last year and hung it with a bungee near the return, but it was after I put in BBB, and I had to readjust.

Last question, what is the best way to clean a sand filter (are the cleaners a scam?) and how often should it be changed? Is it a pain?

[aylad]

Hi Scpool....

Do you already have a chlorine feeder? Or are you planning to buy one? They can be used successfully with trichlor pucks (that's the ONLY kind of chlorine you put in a trichlor feeder!) but you have to keep a close eye on your pH and CYA levels. They actually work better as a supplement to bleach than they do as the sole chlorine source for a pool, especially one in your climate.

Adding CYA is not going to substantially lower your pH, whether you add it through sock or skimmer. What exactly are you adding when you say you added BBB and had to readjust?

[AnnaK]

I use an in-line chlorine feeder with 3" trichlor pucks. I also use liquid chlorine which I buy in 3 gal carboys at the pool store. The primary concern with using trichlor pucks exclusively is the buildup of CYA during the season, and the higher it is the more chlorine you'll need to maintain a sanitized pool free of algae. In my case, I have a lot of splash-out requiring frequent additions of water. I once calculated that I probably replace 1/3 of my pool's volume each swim season. Hence, CYA buildup isn't a concern in my system.

At the beginning of the season there is no CYA in my pool. I normally close with CYA around 60.

When I first open the pool I add enough granular CYA to get to around 30 ppm. I also adjust FC, TA, and pH to the values I prefer. Then I run the in-line chlorinator at a setting of 1/4. This is where it gets tricky because the chlorinator only puts chems in your pool when the pump is running, of course. My pump is on for 6 hours out of 24 and I've learned that the 1/4 setting maintains the FC at around 3 ppm. If I ran the pump more, I'd get more chlorine, more CYA, and might experience a pH drop.

By the middle of the season I have all the CYA I need and turn the chlorinator off. That's when I go to strictly liquid chlorine, about 1.5 cups per day, depending on use. When I notice the FC dropping more than expected from use, I test for CYA and may add some. The chlorinator gets turned on again when we go on vacation or away for a long weekend.

So yes, they can be used successfully but I would not use it exclusively.

[SCpool]

Oh wow, you are both so helpful. Yes, I was just supplementing with the pucks, but primarily using bleach. I'm right on the coast, it gets very hot, and my pool is in full sun until about 4 pm. I do not have a feeder currently, I was putting a puck or two in the skimmer daily as a supplement and have had no problems with algae since I've been on BBB. My concern is that I travel in the summer and wanted to be able to have an easier system set up for my house-sitters when necessary. I will definitely follow your advice and start with lower CYA (30) because my system will build up. I don't have a ton of splash out, but a lot of evaporation. It is HOT here.

My curiosity peaked when you mentioned running your pump for 6 out of 24 hours. I've been advised (perhaps, ill-advised) that in my climate in the height of summer, I should run my pump continuously. Is that overkill? Early in the season, I don't run it continuously, but I have been in June, July, and August.

To answer Aylad's question, I feel like I am constantly having to raise my pH. But since I've only been at this pool thing a few years, I have a lot to learn. I also thought I was spending a lot of money on BBB, and then I realized what other people pay at the pool store and realized that I am NOT spending a lot of money. So perhaps it is normal. I end up adjusting (raising) the pH about every 3-4 days (and it was late in the season). I couldn't think of reasons why the pH was changing, but you guys mentioning the build of stabilizer from the trichlor makes sense. I certainly can switch to just bleach mid-season and reserve the pucks in a feeder for when I'm away intermittently.

I discovered the pool calculator online this year and was going to use that to set my values. What do you guys use?

[AnnaK]

I use the pool calculator. If you save it as an HTML file to your desktop (or favorites) you don't have to be online for it to work. I have it as a file on my iPad as well and use it at the pool to calculate chems.

What is your TA (total alkalinity)? TA acts as a buffer to keep the pH from fluctuating too much. In my vinyl AGP I run it at 80 ppm which is the TA of my fill water. It does a great job of keeping the pH stable (7.5 nearly all the time). Because of the splash-out and refilling with TA=80 water my pool seems to stay at a Zen state :)

Ok, pump run time. That varies hugely based on type of pool, bather load, environment, water temp. The goal is one full turnover of the water volume each 24 hours through the filter. I have absolutely no idea how you calculate that but clearly, there are ways. From experience, I've learned that 6 hours does it for my pool. How do I know? No algae, clear, sparkly water, steady chemical balance day in and day out, no chlorine smell, bottom feels squeaky clean, not slick or slimy. IOW, my pool is clean. I had it at 8 hours and saw no difference but at 4 hours I noticed the pool bottom feeling slick and that's the beginning of an algae bloom. So, 6 hours works in my environment. Your water is likely warmer than mine and 6 hours would perhaps not be enough for you.

I would cut it back to 12 hours on, 12 hours off. You'll know if this isn't working within a few days. If you start seeing problems, treat the water and go with 16 hours. But if, after a week, your water is good and there's no indication of a dirty feeling of the liner, cut it to 10 hours, see how that goes. Or you could go high tech and find out how to calculate the turnover time required for your volume :)

Basically, it's all a matter of getting to know your pool. Each one is different. All we can do if speak in generalities; each pool owner needs to keep records, observe, understand how the chemicals work together, how to test the water, how to be pro-active, how to do damage control, and why it's not ever necessary to freak out if the chems are off or the water gets a green tinge. It happens. We know how to fix it. I use a notebook and put down test results and observations. Weather, heavy pollen load, clean pressure after backwashing, how many dogs were in the pool, chlorinator settings, that sort of thing. If the bottom feels a little slick I add some extra bleach, brush it, and give the pump an extra hour that day (or night).

When I go away for a few days, I make sure I have a good chemical balance, turn on the chlorinator, and cover the pool with the solar cover. In the absence of a bather load I usually wind up with more chlorine than necessary when I return and everything else steady.

Sorry, you didn't want a book, did you?

[SCpool]

I did want a book! This has all been SO helpful!! I know exactly where I need to start and the course I am going to maintain. And conveniently, I am physics teacher and can totally calculate the flow rate turnover in my pool! YES!!

One last question: what do you use to clean your sand filter and how often do you clean it? How often do you replace it? I think the filter is working fine, but it could be what I am just used to, you know what I mean? When the PSI goes up, I backwash and I know what my clean pressure hovers around, but wondering if a clean pressure of about 19 PSI is normal.

[aylad]

Clean pressure is different for different filters. Contrary to popular belief, you should never have to replace the sand unless you really get it gunked up (Baquacil conversion, overkill on suntan lotions and oils, etc.). One or more of our mods is going over 10 years with the same sand! You don't really need to use anything to clean the filter, except backwashings when the pressure indicates. You need to backwash when the pressure rises 6-8 psi over your "clean" pressure. As long as it's doing an effective job of keeping your water clean, then you're good!

I do agree with Anna that you can cut your pump run time from 24 hours to something shorter. In my pool, 6 hours or so daily (26K gallons, 300# sand filter) works, but to make it easy during the summer I just turn it on when I get up in the morning and turn it off sometime after dinner :)

[PoolDoc]

And conveniently, I am physics teacher and can totally calculate the flow rate turnover in my pool! YES!!

Sorry to pounce on your thread, but I saw your note. High school or college? I'm looking for someone who can do differential error analysis of pool test & dosing activities -- I'm really tired of various resources that instruct people to add "6.17 lbs of Alkalinity increaser to increase their Total alkalinity by 23 ppm".

I know this sort of instruction is stupid, but I need a big scientific hammer to SQUASH it with. End-to-end DEA of the testing and dosing process IS that sort of hammer, but unfortunately, I lost the ability to do DEA 28 years ago (about 6 months after I learned how!).

[SCpool]

Hi PoolDoc,
High school, it used to be in my realm to do that when I was in grad school, but those days are long gone for me too. AP Physics no prob, but DiffyQ would take a hefty amount of re-studying on my part.

Thanks Aylad about the sand filter advice, it actually runs just fine, I only became concerned when other people told me that I "needed" to replace the sand. Thanks again! I'm going to print this entire thread!

[AnnaK]

One last question: what do you use to clean your sand filter and how often do you clean it? How often do you replace it? I think the filter is working fine, but it could be what I am just used to, you know what I mean? When the PSI goes up, I backwash and I know what my clean pressure hovers around, but wondering if a clean pressure of about 19 PSI is normal.


The sand in my filter is 7 years old. I've never replaced it. My clean pressure is 12 PSI and I backwash/rinse when it gets to 18 PSI. I backwash/rinse at the end of the season before I drain the filter. After the equipment is hooked up again in the spring and the filter is full and functioning I put it through a 30 second backwash/rinse cycle to sort of fluff up the sand. Don't know if that's necessary though. I just checked my log book: Last season I backwashed 3 times, so that's about every six weeks during the swim season.

Something that really helps keep your filter cleaner are skimmer socks. I buy mine at the pool store. They look like white knee-hi ladies' hose. You put them inside the skimmer basket and fold them over the edge of it and they act like a coffee filter of sorts. They'll catch pollens (which will look like yellowish gunky stuff similar to drywall mud), tree bracts and flowers, algae, small bugs and etc. I generally check the skimmer sock a couple times each day. They can get very dirty and can impede flow. Rinse it out under running water and put it back in. Be sure it's inside the basket, you do not want it to get sucked into the pump pot! Here, they cost about $7 for five and five will last me two seasons.

Some pool owners use regular pantyhose which can be cheaper than commercial skimmer socks. I've never tried it.

So do tell, how do you calculate turn-over?

[aylad]

I second Anna's suggestion to use the skimmer socks--they're well worth the investment and you'll be AMAZED at how much junk they catch before it gets sucked into the filter, thus decreasing the frequency that you'll have to backwash.

Janet