Super high combined chlorine

[chem geek]

So, with the bucket test thing I guess I am trying to create a mini version of my pool?

Yes, that is correct. It's just easier and less expensive than dumping a bunch of chlorine in the pool. If the amount left is huge, then water replacement could be cheaper/easier.

Your high chlorine demand at the end of last season when the CYA was still high was likely due to nascent algae growth since you'd have to maintain a much higher FC level to prevent that and have to shock at even higher levels. The water probably had lots of nutrients for algae as well. When you closed for the winter, the FC went to zero and bacteria had a great time dining on the nutrients in the pool including the CYA that was there. If the CYA dropped from 100 to 30 ppm, then that 70 ppm could get converted into around 20-25 ppm ammonia that would require roughly 200 ppm FC to get rid of. That's worst-case, but is an extraordinary amount of chlorine required to be cumulatively added.

[themaccs]

It is easy to get frustrated with it, and to doubt yourself, and to just "give it back" to the pool store--but believe me, you'll have this problem fixed soon and enjoy a whole summer in a clean, clear pool, where if you go with the pool store, this is a battle you're gonna fight all summer long. Patience is hard to come by sometimes, but it's a necessary evil!!

We're glad you're here....

Janet

Thanks for the encouragement. I guess I'll keep chugging away with the bleach. We're kind of at a stand still today - the good news is I'm able to keep the FC up with a dose every few hours and the CC has been between 0.5 and 1.0 all afternoon (1 drop almost clears the pink, 2 wipes the pink out easily - I would try a 25ml sample but I don't want to use that much reagent). I have managed to keep the FC between 10 and 18 all day (CYA is 40). The bad news: every time I test the results are about the same: losing about 4ppm FC every 2-3 hours, CC staying at between 0.5 and 1.0 ). I feel like this is the same place I was yesterday when the sun was shining, then the CC jumped up to 2.0 when the sun went down. I've used close to 75 gallons of bleach so far. I hope I am getting close! And I know it will be worth it when I have the rest of the summer with a clean clear pool without daily trips to buy more bleach! Thanks again for the encouragement!

[themaccs]

If the CYA dropped from 100 to 30 ppm, then that 70 ppm could get converted into around 20-25 ppm ammonia that would require roughly 200 ppm FC to get rid of. That's worst-case, but is an extraordinary amount of chlorine required to be cumulatively added.

So if my math is right (and I'm not at all sure it is), 200ppm FC calculates out to roughly 70 gallons of bleach in my size pool (19,400 gal). I have used about 75 already, so hopefully I will be done soon. Unless of course the scenario is really much worse and my CYA was much higher at the end of last season. I know when I first discovered how high it was it was over 150, but we did drain some and dilute and I'm pretty sure I got it down close to 100 - but I know I was still having to dilute my sample to be able to test it, so it may have been higher. Ugh! After putting all this into it, just not too sure I'm ready to drain and dilute. We would be hiring someone to do that since i am not willing to risk messing my liner up doing it ourselves, and that would surely be more costly! Thank goodness for Sam's and cartons of big jugs of bleach!!

[chem geek]

You are at the point now where you need to measure the FC loss overnight when the sun is not on the pool. I suspect that this may not be a very big loss in which case sufficient CYA in the pool should protect the FC from dropping too much during the day. I think you are pretty close to being done -- at least I hope so.

[themaccs]

Well, I think I am seeing the light at the end of the tunnel!!! An hour ago I added 2 quarts and 2 cups of bleach to get FC to 16 because I had a FC of 12.5 and a CC of between .5 and 1.0. It's still light but no sunlight hitting the pool. Took a walk and tested again: FC now 15.5 and CC 0.5 - 1st time I've cleared the CC with 1 drop since I started this thing!! Plan for tonight is to continue to test hourly and add bleach as needed until about 11 when I go to bed - then see how the FC holds overnight, testing 1st thing in the morning. Thanks for the help and encouragement!

[chem geek]

It does sound like you are near the end. Just keep in mind that the easy stuff that oxidizes readily has been taken care of, but there may still be some remnants of partially oxidized CYA that will be somewhat slower to oxidize and get rid of. You are definitely close and should see your total chlorine demand go way down at this point.

So if your CYA is low, raise it so that you don't lose too much from sunlight during the day. You should have it at least at 30 ppm, but 50 ppm is fine as well and is more typical for pools in the sun (pools in a LOT of sun, such as Arizona, sometimes operate at 80 ppm to minimize chlorine loss, but you have to be very diligent about maintaining chlorine in such pools since it takes more chlorine to shock them to get rid of algae).

It's interesting (and somewhat comforting to my nerdy personality) that the total amount of chlorine needed was in the ballpark of that predicted based on the CYA loss, which was a rough guestimate to begin with.

Richard

[themaccs]

So if your CYA is low, raise it so that you don't lose too much from sunlight during the day. You should have it at least at 30 ppm, but 50 ppm is fine as well and is more typical for pools in the sun (pools in a LOT of sun, such as Arizona, sometimes operate at 80 ppm to minimize chlorine loss, but you have to be very diligent about maintaining chlorine in such pools since it takes more chlorine to shock them to get rid of algae).

It's interesting (and somewhat comforting to my nerdy personality) that the total amount of chlorine needed was in the ballpark of that predicted based on the CYA loss, which was a rough guestimate to begin with.

Richard

My CYA was at 40 when I checked it earlier today - I had to use a little stabilized chlorine yesterday morning when i ran out of bleach. So it looks like I am good there. We do get a lot of sunlight on the pool, so I will have to see how that goes once I see whether or not I am loosing any at night. I think I will be able to get home mid-day tomorrow to check on it.

I am still loosing a bit of FC, just added 1 quart + 3 1/2 cups because it had fallen to 14.5 and the CC was back up a little over 0.5. But it is nice to be adding bleach using my pint measuring cup rather than by the jug full!

I can appreciate the comfort you receive from knowing your guestimate was in the ballpark - my personality works the same way.

The cloudiness in front of the light in my pool is nearly gone as well! YAY!!

Thanks again for your support and encouragement - not to mention your willingness to share your knowledge and experience!

[themaccs]

Well, i am still fighting, but perhaps not quite so hard. FC dropped from 15 last night to 10.5 this morning. CC was at 1.0 last night, up to about 1.5 this morning. I added 1 1/2 of the large (182 oz) jugs of bleach (so about 275 oz). Rest of my numbers look like this: pH - 7.2, TA - 150, CH - 200, CYA - about 45. I plan to come home mid-day to check on it.

[aylad]

Sounds like you're almost there. You'll know for sure when the Cl stops dropping overnight, when tested in the evening and again in the morning before the sun hits the pool. Just a note--I'm one of those that keeps my CYA intentionally 80-90 because I live in Louisiana with my pool in full sun all day. If I keep my CYA below 60, I lose almost twice as much chlorine during the day as I do with my CYA at 80. It's an unusual case, I know, but I'm just saying it happens.........

Janet

[themaccs]

Mid-day not too bad - FC - 11, CC - just over 0.5 (1 drop almost cleared it). So another jug and 1/2 of bleach (about 270 oz). Seems like i haven't really lost much more FC between 6:30 am and now (1:10 pm) as I did between 11:00 pm and 6:30 am this morning - almost the same number of hours, but a LOT of HOT Sunshine today.