LQ- dilution % cycling over time

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T

texasmax

0
May 24, 2010
200
Dallas, TX
All-

First of all, appreciate all the great advice and learnings I've picked up on this board- so thanks to all of you!

Installed my LQ, along with the 3/8" conversion, 2 days ago. Using 6% bleach (local Costco has 3x182oz jugs for $7.15 + tax!). Have the 8 gallon model and started with 5 jugs (a bit under 7.5 gallons). Monitoring it as time goes to see what my equilibirum point is, though right now I'm estimating a refill every 4 days or so. Question- clearly the LQ mixture is strongest immediately after a refill, and is weakest just before a refill. Yes I'm going to monitor for myself, but can't wait to hear what others have found!- do you see pool FC highest after a refill, and lowest just before? I can see for quick refill cycles (every 1-2 days) this won't make a difference. But for longer cycles, upwards of a week, have people seen any sort of FC level cycling? If so, is the answer to just do partial refills more frequently?

Thanks! :)
 
Welcome to TFP.

I think you are about right with your expectations. If I have time, I'll add a jug whenever there's room. If I'm busy, I may let it get down in the tank and it doesn't feed quite as much chlorine.

Fortunately, it's kind of a self-regulating cycle. In nicer weather, we swim more, which along with the sunshine uses more chlorine, but I'm around the pool more, so I add more often. If the weather is cloudy and rainy, I'm out there less, but chlorine use is lower.
 
I haven't noticed a marked difference in the FC level whether just before or just after a fill. I also don't find that I have to adjust the flow very much once I have things lined out . I have the 8 gallon model too and usually let it get down to about 2" of chlorine left before a refill.

If you think about it the water/chlorine interface stays the same so the rate of dilution stays the same, unless of course you let it run completely out of chlorine.

I'm interested to know what size your pool is? It must be huge for you to think you'd use 8 gallons of bleach every 4 days? I have to fill mine up about every 20 days for my 13,000 gallons.
 
Thanks! I hear you on the constant interface; makes sense that the rate of bleach "crossing the boundary" into the water remains constant.

I've got a 16k gallon pool, full sun. I ran it at 4.5-5 on the flowmeter and it added 12 FC in 6 hours. I turned it way down since, but figured in I was leaving at that high a flow, given how much bleach would have been used already to get the FC that high (based on pool calculator). So maybe it will go a lot longer :) Never ran a chlorine demand so let's see how it goes.
 
So, first of all, have plenty left in the tank :)
16k gallon pool, pushing 105gpm on a single-speed pump. Water's 80 degrees, and run the pool 5 hours a day (except for testing out new configs like now) for the time being (have a 2-speed motor in the garage, just need to find the time to install!). CYA's been solid at 35 for a year; did a partial drain after it hit 100 (used trichlor, changed and using calcium hypo for chlorination since).

You asked for numbers... :)
5/25 3pm: FC=0, TC=0, alk=85, ph=7.8, added 16oz HCl, then turned on LQ for first time, w/ LQ flowmeter at 4.5-4.75
---running for 6 hours
5/25 9pm: FC=12, set flow to ~1

5/26: ran for 5 hours

5/27: ran for 5 hours; 2 hours in: FC=3.5, CC=0, pH=7.4, alk=70, CH=250, added in ~16oz of baking soda, changed flow to 2

5/28: ran for 5 hours, at end of run: FC=.75, CC=0 (by the way, using FAS/DPD), flow was at ~1.25, upped it to 3

So here's the LQ effect (flow readings drifted over time, taking an average here):
6 hours @ 4.5, added 12FC (+2FC/hour at 4.5)
7 hours @ 1, dropped 8.5FC (-1.2FC/hour at 1) (at this point I think 2.3 is my equilibrium point, where FC addition=consumption)
8 hours @ 2, dropped 2.75FC ( -.34FC/hour at 2) (still looks like my target is 2.3-2.4, but need to get my FC up to a proper level)

will post more this weekend!
 
Another method to consider. I have an all original LQ and have set the flow control to approx 3.5, after that I do not adjust the flow control because I consider it is difficult to gauge the adjustment. I run my pump two periods a day and adjust the time on to get a constant FC reading (at the same time every day). The FC will vary depending on the weather and swimmer load but evens out pretty steady. You can always run the pump a little extra to increase the FC if necessary.
 
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