Questions using an In-line Trichlor feeder and water chemistry

smerls

New member
Aug 1, 2017
4
Arlington, MA
I have a couple questions regarding the use of Trichlor tabs using an in-line chlorinator. The questions are listed below if folks would like to skip the background, sorry if the background is a little long but I think I over thinking this instead of keeping it simple but I would like to understand using trichlor better and the background explains why I am considering using the tabs.

Also, I know trichlor tabs are not recommend because of the CYA/Ph it add so again i’m asking these questions to educate myself further on their use. I am considering switching to a SWG but in the meantime I would like to go back to using the Trichlor tabs for it’s convenience.

Just so folks know, I inherited the pool from my father when he passed a few years ago. The pool is over 35yrs old (it was re-surfaced in 2014). My father used a hybrid BBB method that is He stayed away from the pool store as much as possible, did his own testing, used Muriac acid/backing soda along with the trichlor tabs while also using poly 60 and he would “super chlorinate” with powdered shock about once a week. Although I had old test kits where he tested for calcium hardness and probably CYA etc, the last few years when I helped him he only tested for Free/combined chlorine and for TA/Ph. He did not bother too much with CYA unless it was low to start the season with. Also he was retired for at least half the time he owned the pool and he was probably out there every day or other day brushing the pool.

In any case he never seemed to have a problem with the pool, he did say he had an algae bloom once which I don’t recall but the water was always crystal clear even using the trichlor tabs. I imagine he did not have a problem because we live in MA, the season is only 5 month long (from mid may to mid Oct) and between pool use, backwashing and rain there was a good amount of water replacement.

I Inherited the pool about 3yrs ago and have a love/hate relationship with it. I have also been struggling a bit with it. Although I grew up with the pool and helped my father with it towards the end, I really did not learn what I should have when he was around so I am not quite a begginer but I am not an expert either and still trying to find my way.

In the first year we did not open the pool until July and it was a mess. At this point I found trouble free pools and was using the TF100 test kit but was not confident in my results so I would go to the pool store to check my results. Just when I got the pool sorted out, the pool store (as I was warned here would do) was pushing phosphate remover. Since it was only about $7 bucks (it was on sale), I bought to be nice since the testing was free. I was not going to use it but I did (as it said you could put it in the pool and swim 15 minutes later) and that turned out to be another two week mess which I will never reapeat. By the time everything was settled the year was over.

The second year I was going to split how I was using the chlorine. For the first half May/June, I was going to use liquid chlorine and then in July I as going to switch over to trichlor. The reason was for convenience and because we usually go on vacation toward the end of July/August and to help manage CYA levels. Using the liquid chlorine worked out well but when I switched to the tabs it seemed to work for a week or two. After a week or two although the CC levels never got past .2 it was always under .5 , I did start seeing some green that looked like Algae, around the pool including the string for thermostat, around the plastic flap of the skimmer and I believe there a little on the walls in a spot or two. I was not sure if this was because I was not brushing enough or I switched from running the pump from 12 hours to about 9 (as we only get full sun for about 4+ hours a day) or because of the switch to the trichlor (FC was still within target for CYA through the week or two). I then switched back to liquid chlorine for the rest of the year and switched back to 12 hrs running the pump.

Last year I stayed with liquid chlorine. When it turned hot in mid July I did start using a little poly 60 and although the pool is not used that much when it was used I did “super chlorinate it a couple times” afterwards. The readings were all fine and did not have any problems with the algae.

I should note that the last two years my CYA started high about 60 but since I only used tabs when I went on vacation (and stopped using them after a week or two the previous year) it never got past 60 and actually came down to 50.

Although I did not have any problems, I did start to smell a little bit of chlorine. It was not overpowering but I had one or two people say they could smell it when they were outside the pool and then I thought I was smelling it also. Again it was not that strong but seemed strong than I ever remember it. Interestingly my CC’s stayed below .5 mostly at .2 or less so I don’t know if I was starting to get chlorine lock or I was just imagining it but it did bother me.

On the positive side last year I did find a bit of a grove that is I started to learn how much chlorine to add each day without measuring and how much acid I could put in. However it did get to be a pain lugging the bottles around.

So for convenience and with the short season (we have a full winter close, where we empty the water about 1/3 and put on a hardcover.) I am considering going back to using the Trichlor tabs with an inline feeder but I have the following questions.

  • When using an in-line chlorinator, since it is continually feeding chlorine to the pool, unlike using liquid (if you don’t have a pump) would this be more like using a SWG? Should I be following the Chlorine/CYA for SWG?

  • Similar to question 1, if I use the trichlor and the more traditional method including “super chlorinating” and using poly 60 would I only need to keep the FC at around 3-5 (as my father did), would that be enough to keep the pool sanitized even if the CYA goes higher?

  • I know having a CYA over a certain point is a disaster but if using this method does the CYA matter less as long as I don’t go over a certain point (I will still be testing and watching it). If it goes up to 80 or 90 for example would I still be ok (again remember this is a short season)?

  • I hope this question makes sense, in my head it does but so doesn’t a lot of other things…anyway two years ago when I switched to trichlor tabs in the middle of the season when it was hot, I started seeing Algae on the thermometer string and a bit around the skimmer etc after about a week or two, even though FC levels were within target for CYA. Could this have been because was this because the trichlor needs to “build up”. (I am not quite sure how to explain what I mean by build up). When I say “build up” I don’t mean in terms of the FC getting to a certain point, it was already at the target for CYA when I switched. In the past when we used trichlor it was used starting at the beginning of the year when the weather was still colder. When I switched it was when it was hotter. So would the trichlor need some time to build up in the pool, would it need to deliver a certain amount for a certain time to stabilize the water?

  • Finally with such a short season would people still recommend SWG if my goal is not having to lug bottles of chlorine around, deal with chemicals and have to do a daily dose? Also I am aware that you need to clean the cells every so often and if you are going to slam you need to use liquid to do so but I am ok with that, I just want low maintaince?
Anyway I guess what these questions come down to is, if I use the trichlor tabs (with poly 60 and “super chlorinating) which would constantly (while the pump is running) feed the pool with chlorine, should I then follow the Chlorine/CYA for Non SWG or should I follow it for SWG and can I get away with having a higher CYA (if it goes up into the 80’s/90’s) while keeping the FC lower, again 3-5 for sanitizing?

Again sorry for the long post but I am just trying to educate myself more and I appreciate any thoughts!!
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome to TFP! :wave: I'll get right to your questions:
- SWG and tabs are different beasts, so you cannot try to compare the two. The only similarity is you aren't adding liquid chlorine daily.
- FC must always be balanced to the current CYA for your pool type (non-salt) per the FC/CYA Chart
- With such a short season, a SWG is a toss-up. But less usage means it should last longer as well.
- Since you are expected to exchange a good amount of water each year, especially for winterizing, the CYA should fall which makes tabs a little more usable. But you should never rely solely on tabs all season long.
- There should never be any reason to super-chlorinate. Weekly shocks are a thing of the past (pool store stuff)
- Don't try to use Poly 60 during the regular season. You're just wasting money as the chlorine will eat it up. Save the Poly for winter closing.
- If you rely on tabs exclusively, your CYA will climb fairly quickly. In a non-salt pool and moderate temp location such as yours, there's no need to have a CYA over 50 I would think. You can go higher (70 max), but the FC needs to be maintained with it.
- Since you seem to travel late summer, I would use liquid chlorine early in the season, then tabs when you are away; maybe supplement with chlorine if a friend or neighbor can help.

Hope that helps.
 

smerls

New member
Aug 1, 2017
4
Arlington, MA
Hi Texas Splash,

Thank you for the welcome and the reply I do appreciate it and it does help!! Also hope you did not get hit too hard with the recent cold spell!

I guess I was thinking that because the tabs continually feed chlorine that it might be a little different than liquid and more similar to SWG but I guess it is not. Also I know that in some cases it is recommended to have higher levels of CYA, in areas that are hot, dry and have direct sunlight like Arizona.

In any case I will have to look into converting to a SWG at some point, and will probably continue like I did last year with the liquid and then switch to the tabs when I go away.


Thanks Again!!
 
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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter

Bperry

Gold Supporter
Aug 20, 2020
208
Knoxville, TN
Pool Size
27000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
Hi Texas Splash,

Thank you for the welcome and the reply I do appreciate it and it does help!! Also hope you did not get hit too hard with the recent cold spell!

I guess I was thinking that because the tabs continually feed chlorine that it might be a little different than liquid and more similar to SWG but I guess it is not. Also I know that in some cases it is recommended to have higher levels of CYA, in areas that are hot, dry and have direct sunlight like Arizona.

In any case I will have to look into converting to a SWG at some point, and will probably continue like I did last year with the liquid and then switch to the tabs when I go away.


Thanks Again!!
One of the other drawback of the pucks is that they are so acidic that they drive the pH down and if not managed, can drop it low enough to start corroding metal parts in the system (a heat exchanger if you have a heater being particularly susceptible).
 

CrystalRiver

Well-known member
Jun 19, 2020
522
Massachusetts
The pucks continue to dissolve in your feeder while the pump is off, sending a super acidic slug through the system when you do turn the pump back on. If you have a feeder and a heater, you need to be sure the feeder is plumbed after the heater.

As for using poly during the season, just say no. As PP said, it's just burning up your chlorine. And the ickies (viruses and bacteria that can actually make people sick) grow at lower chlorine levels than algae does. Algae is slimy and unpleasant but not harmful - but if you have algae, you also have an unsanitary pool full of ickies. Using polyquat to try to keep the algae at bay just covers up the problem, and leaves you with a pool full of ickies.

There's no need to super chlorinate during the season, either, as long as you follow the FC/CYA chart. Yes, after heavy bather load, you will need to top off the chlorine level - just bring it to the top end of the target range. The leftover waste from swimmers will consume a little extra chlorine. As long as it never drops below the minimum, all is good. Just like you learned what your pool needs as far as daily chlorine and acid usage, you'll quickly learn how much chlorine to add following a swim. Just don't get too lazy and forgo testing altogether, lest things get out of whack while you are ignoring them.

Long term, I think you will be happiest with a SWG. I'm probably making the jump this season, in large part due to covid and anticipated shortages.

Play with Pool Math some to see the effects of using pucks. Think about how many you would throw in for a week, or however long you're usually away, and see how much CYA they add. Pucks are fine for short term once you understand water chemistry and all of the things the pucks add. It's much easier to adjust one parameter at a time, by adding liquid chlorine separately from dry CYA separately from acid. With pucks, you get all three, can't control the ratios, and how much dissolves on a given day is not controllable, either.
 

smerls

New member
Aug 1, 2017
4
Arlington, MA
One of the other drawback of the pucks is that they are so acidic that they drive the pH down and if not managed, can drop it low enough to start corroding metal parts in the system (a heat exchanger if you have a heater being particularly susceptible).
Hi Bperry, I have not logged in for a bit, so I missed a few posts. Actually this was a problem, when my father was using the pucks, we often had to add backing soda to make sure the ph was high enough. The last year or two when I stopped using the pucks, it went the other way every know and then I had to use the acid to bring it down.
 

smerls

New member
Aug 1, 2017
4
Arlington, MA
The pucks continue to dissolve in your feeder while the pump is off, sending a super acidic slug through the system when you do turn the pump back on. If you have a feeder and a heater, you need to be sure the feeder is plumbed after the heater.

As for using poly during the season, just say no. As PP said, it's just burning up your chlorine. And the ickies (viruses and bacteria that can actually make people sick) grow at lower chlorine levels than algae does. Algae is slimy and unpleasant but not harmful - but if you have algae, you also have an unsanitary pool full of ickies. Using polyquat to try to keep the algae at bay just covers up the problem, and leaves you with a pool full of ickies.

There's no need to super chlorinate during the season, either, as long as you follow the FC/CYA chart. Yes, after heavy bather load, you will need to top off the chlorine level - just bring it to the top end of the target range. The leftover waste from swimmers will consume a little extra chlorine. As long as it never drops below the minimum, all is good. Just like you learned what your pool needs as far as daily chlorine and acid usage, you'll quickly learn how much chlorine to add following a swim. Just don't get too lazy and forgo testing altogether, lest things get out of whack while you are ignoring them.

Long term, I think you will be happiest with a SWG. I'm probably making the jump this season, in large part due to covid and anticipated shortages.

Play with Pool Math some to see the effects of using pucks. Think about how many you would throw in for a week, or however long you're usually away, and see how much CYA they add. Pucks are fine for short term once you understand water chemistry and all of the things the pucks add. It's much easier to adjust one parameter at a time, by adding liquid chlorine separately from dry CYA separately from acid. With pucks, you get all three, can't control the ratios, and how much dissolves on a given day is not controllable, either.
Thanks Crystal River!

No heater and the trichlor feeder that is installed is after the filter and all the equipment and it is designed for the pucks but I still need to be very careful with the pucks as in the past just getting a good whiff of the chlorine when taking the top off is not pleasant.

Old habits are hard to break, even last year where I was using mostly liquid chlorine and everything was in balance I had to resist the urge to do something , or the feeling that was brewing in the water.

I'll probably just go back to the liquid chlorine for this year but I am definitely going to look into SWG, as I get older I want to deal with as few chemicals as possible.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
15,922
Evans, Georgia
For a pool with only 4 hrs of direct sunlight, and if you have a light bather load, I would only use 30, maybe 40ppm of CYA at the most. This will allow you to use less liquid chlorine on a daily basis, but which you can bolus with when its a party :party:.

Maddie 🤘
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
11,114
Franklin, NC
Hi Bperry, I have not logged in for a bit, so I missed a few posts. Actually this was a problem, when my father was using the pucks, we often had to add backing soda to make sure the ph was high enough.
I will just point out, baking soda raises TA, not pH.

pH can be raised in three ways: borax, soda ash, and aeration. Borax is usually the best choice. Borax raises the pH and also raises the TA level just a little. If your TA level is low soda ash will raise both the pH and TA levels. If your TA level is high, aeration is best as it will not raise the TA level at all. However, aeration is rather slow compared to the other two.

 

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