Can I maintain FC level with bleach?

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Rob621

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May 4, 2010
71
Lehigh Valley, Pennsylvania
I recently switched from pucks to bleach. All is going well. However, I noticed everyday a significant drop in FC level. CYA around 40-50 so I shoot for an FC level of 5-6 ppm. I add bleach in the evening to get this level and when I get home the next afternoon, I'm usually down around 1-2 ppm FC. I add bleach and bring it back up to around 5-6 ppm and so on and so forth each day. The pool is in full sun and it's been in the upper 90's recently in PA. Should I be concerned with this significant drop every day? Is there a way to maintain the level using bleach? This is an advantage to the in line's with the pucks, that they maintain a relatively consistent CL level (I understand the disadvantage of the CYA). I guess the real concern is continually dropping below my minimum FC level and the potential for an algae outbreak. Fishing for any thoughts on this.

Thanks,
Rob
 
Adding bleach every day or two during the summer is normal.

If that's a drag, you have a couple of non-puck automation options. You can investigate a bleach feeder such as a peristaltic pump or The Liquidator; you can also look into using a SWG.
--paulr
 
I guess the real concern is continually dropping below my minimum FC level and the potential for an algae outbreak. Fishing for any thoughts on this.
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If I am reading this correctly, you are actually losing 4 or 5 ppm FC daily?

If yes, then that seems high. I suggest an overnight FC loss test. Also, try raising FC to 8 ppm each evening. This is the high target for CYA of 50.
 
If you post a full set of test results, I believe I would suggest going to 50-60 CYA. That should reduce your FC consumption to a more normal 2ppm daily or close to it.

That said, you don't talk too much about swimmer load. If the pool is really busy, 4-5ppm FC loss is pretty normal. If the swimmer load is light, then I think 2ppm is a reasonable rate of depletion.
 
My CYA level is 50 and I add bleach at nite to jack it up to 8. I'm usually down to 4.5 next evening which keeps me .5 above the minimum of 4 for my CYA level. Pool is full sun ALL day and in Texas. Swimmer load doesn't seem to matter. Considering taking my CYA level to 60 and see if I have less daily loss.
 
Recently, since I got back from vacation on the 28th of June, I have been experiencing the same...My water is fine as it holds overnight...but with the extreme heat we have been having here in the midwest and that they are having out east...there really wouldn't be a surprise to see a FC loss of 3-5 ppm in a 24 hour period. If the FC holds overnight...if you add chlorine or bleach up to 8 ppm at say 7 pm and at 7 am it is still at 7 ppm or higher with CC of less than .5 ppm I would say you are ok and chalk it up to hot hot sunny weather as I have done with my pool...Just make sure you add chlorine at night and check it before swimming...you can always add more...I try to keep my pool at 4-7 ppm FC...But in the heat of the day and full sunshine in my yard...I get the same kind of loss.
 
This is where keeping the CYA level higher helps to reduce chlorine consumption, but with the downside that if any problem occurs that requires shocking, then the shock FC level is much higher. With SWG pools the risk of missing a chlorine dose for a day is low. If you think you can carefully manage your pool with manual dosing, then 80 ppm CYA is OK (with an appropriate FC level). You can use supplemental products or 50 ppm Borates as "insurance" options to help prevent or slow down algae growth in case you miss a dose, but that is extra cost.
 
Rob,

As I was reading your post, I actually had to stop a moment and think about if I had actually posted this message....it sounds EXACTLY like the same issue I'm having -and in Lehigh Valley as well. I just switched to the BBB method, and my pool is also in full sunlight all day and I'm finding the exact same thing as you - adding bleach early evening and by the next day the bleach level is dropping drastically. Granted I've had some very heavy bather loads on the weekends, but I don't truly understand my FC level dropping so much during the weekdays. I'm also around the same CYA level as you.

I guess it's just the sun and heat we're having here in the Lehigh Valley that's causing this!!

I will also say that over the past weekend I had a huge party here with over 75 people, and LOTS of kids in the pool all day. I had the FC level up to around 7 prior to the party and even throughout the weekend, but by July 5th it had plummeted to almost zero. I also ran out of liquid bleach, so I did a shock treatment with my leftover granular trichlor and dichlor pucks and FC is back up to over 7 and holding steady for 2 days now. Seems to me that liquid bleach just dissipates much quicker than the pool company chemicals. Guess that's a tradeoff.
 

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tim_pool_newbie said:
Seems to me that liquid bleach just dissipates much quicker than the pool company chemicals. Guess that's a tradeoff.
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It will be the same FC drop regardless of source at the same CYA level, but if you used to use Trichlor and Dichlor then the CYA level could have been very high so protected chlorine more. Also, you might be maintaining a higher FC/CYA ratio now in order to prevent algae growth using chlorine alone, but that could be higher than what you used to do. For example, you might have had 3 ppm FC with 100 ppm CYA in the past which would use less chlorine in the sun, but would be at greater risk for getting algae. So you are being more conservative now in terms of chlorine, reducing risk.

As for chlorine consumption when all of the people were in the pool, that would create a high chlorine demand regardless, but in the past if using Trichlor pucks in a feeder you were more continuously dosing the pool so the FC wouldn't drop as much as just adding chlorine from bleach or chlorinating liquid in one shot. It's hard to figure out the true FC usage with Trichlor because it's always adding it -- you have to figure it out based on how many pucks you use over time. Also, in terms of weight, Trichlor is more dense with chlorine so it "seems" like a lot less chlorine being used compared to the chlorinating liquid or bleach that is mostly water and thus much heavier to carry (and larger in volume).
 
Just out of curiosity -- when you say you target 8 in the evening, do you actually test to be sure it got to 8? Any chance you are off on the gallons and aren't getting as high as you thought?
 
I am in the Lehigh Valley as well.
My pool gets full sun ALL day, and the temps have been hovering around 100, and my kids have been in the pool every day.
I also have been seeing a significant FC loss (my CYA is ~40-50.)

tim_pool_newbie and rob621: where exactly are you in the Lehigh Valley?
 
We have a solar cover and have been pulling it over every night, and I definitely see less chlorine use. With the close to 100 temps over the past week, we also love our water temp around 90 and the solar cover makes a big differance there.
So a solar cover may be worth the money in your case, with full sun all day.

Dan
 
If you're seeing 4-5ppm loss daily, with a reasonable (50+) CYA level, I'd do an overnight FC loss test...
1) add bleach one evening (after the sun is off the pool) as usual
2) wait an hour with the pump on
3) test to verify what your FC actually is
4) test again in the morning before the sun hits the pool

You should see no more than 1ppm loss overnight.
--paulr
 
If you just want to even out your FC levels you could opt for an automated liquid chlorine dosing system, either the Liquidator or some type of dosing pump. I installed a metering pump about a month ago, and while I am still fine tuning the daily dosage I can see where it will make things a lot easier in the long run.

Ike
 
Isaac (or anyone else) - How easy was it to install a chlorine metering pump (like the Liquidator) post-pool-construction? My pool is brand new, and I wish I had known all this info BEFORE building it, or I would have asked different questions and perhaps had one installed (and left off the Nature2 device!).

I'm also concerned what installing something like this might do to any of my warranties. Perhaps I should at least wait a year or so till the manufacturer warranties are expired on my pool equipment (heater, filter, pump, etc.). Or is it easy enough to justify that one item didn't interfere with another?
 
It depends on your plumbing setup (as long as you inject downstream from all the other equipment I can't see it being a warranty issue, particularly if you include some type of anti-backflow valve) mine is less than ideal, but I worked with what I have. It is mostly covered in this message thread: new-metering-pump-project-t22358.html A lot of my design was working within the limitations of the pump I found on ebay, on the positive side it was under $100, never been used, although some of the accessories were missing out of the box, this model pump sells for around $550 new. In order to avoid outgassing issues I had to install it in such a way that the flow always goes up, therefore the tall pipe going to the feed point shown in the photos. The general recommendation seems to be to use perstaltic pumps ($600- $750 new) for chlorine instead the diaphragm type pump I used, this is due to concerns of loss of prime when dealing with outgassing, so far this has not been a problem for me even with a 4+ day time with the pump off (to let FC level fall back to normal while fine tuning pump settings), I suspect this is due to using one of LMI's smallest metering pumps rated at only .2 GPH max (this is 100% stroke at 60 strokes per minute, mine is currently set at about 70% stroke and 2 strokes per minute, which is getting close to the minimum speed of .6 strokes per minute, minimum stroke length is 30%, but that short of stroke could result in outgassing problems) this still should not cause me a problem hitting minimum flow even if I switch to 12% liquid chlorine, but does show how you have to carefully match pumps to applications. Right now I am running my system 24 hours per day, I need to replace the timer for my water pump, but will wait until cooler weather to do that, and probably integrate that in with some other refurbishing projects.

Ike
 
The Liquidator is not a pump. It is basically just a tank of chlorine and water, with a tubing/float/valve system that diverts some pool water through it, constantly adding a very dilute chlorine/water mixture to your pipes. It should not affect your pool or equipment warranties any more than manually adding liquid chlorine would. It WILL require either drilling 1-2 small holes in your piping, OR cutting pipe to add 1-2 tees inline. The advantage to the tees is that you can easily remove the liquidator and install plugs for winterizing. If you can post a pic of your equipment pad, folks here can tell you exactly what it would entail. Of course a peristaltic pump is a great thing too. With either system I think you'll find you use less chlorine than adding once a day. I know I do.
 

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