First time with the TF-100!

[wysocki]

Finally decided to actually do something about my always-slightly-green pool: bought a TF-100 test kit! Took longer to do the tests than I pictured (about an hour) but maybe it'll go faster with experience. I've been pretty much relying on chlorine disks in 2 dispensers to handle the pool. Coming out of my Southern California Covid Winter, I brushed the pool completely, gave it a couple bags of shock, and cleaned the filter (whew). Now a couple weeks later, the pool looks much better and I ran the tests. Here's the results:
pH: 7.7
FC: 8
CC: 1
TC: 9
CH: 300
TA: 150
CYA: 100

So now, what's the best thing for me to do? I read that the CYA indicates draining the pool! Is that safe to do on a plaster pool? I really don't want to be a daily slave to the pool, adding liquid chlorine, and I don't have a salt pool. The pool gets minimal use and I have a Kreepy Krauly that does a nice job of sweeping algae, so I just want a compromise solution: not perfect, but manageable.

 

[Texas Splash]

Well, a CYA of 100 (or more) is a priority because to avoid algae you have to maintain a much higher FC level. Your CC is also a bit elevated, may be nothing, or may be early signs of algae. Either way, you don't have to drain the pool completely, but I would try to exchange about 35%-40% then check your CYA again. Once you confirm the CYA is down to say 70 or below (50 would be ideal), balance the FC level according to the FC/CYA Levels and monitor for a day or two. Keep an eye on FC consumption and that CC level. If the CCs don't fall to 0.5 or less and/or you lose FC rapidly in a 24 hour period, consider doing an Overnight Chlorine Loss Test.

Your TA could come down a bit, but not priority at the moment. Tackle the CYA first and stick to liquid chlorine and let's see how things go from there.

You do mention the Krauly sweeping algae, so that needs to be addressed with a SLAM Process, but only after you lower the CYA. Once you get the CYA down and remove algae, the rest should go much easier. But chlorine will need to be added just about each day or every 2 days at most. Stay away from tabs/pucks. Nice testing.

 

[willygee]

My numbers similar to yours ,CYA 100 ,TA slightly lower. I run FC between 7 to 10..pool water nice and clear for over a year now. LC and MA only chemicals we use. I may post to see if i should run higher FC vs drain down to lower CYA.

 

[kellyfair]

Check out Chlorine/CYA chart, linked in my signature.

 

[willygee]

thanx kf..min 8 ,target 11-13

 

[wysocki]

Thanks for all the replies. Brings up two questions:
1. Could I live with 100 CYA? Would it just mean that I'd be adding more chlorine?
2. Changing the water has complications. If I open the drain valve on my filter, I could only drop the water about 2 feet before the side intake would suck air! (or would the system somehow switch to just intaking from the bottom drain?).
Since I live on a hillside I could siphon the water with a hose, but just draining 15k gallons could take days. Then add the time needed to refill. All this time without running the filter?

 

[mknauss]

Did you do the dilute test for CYA to be sure it is only 100?

You can live with CYA of 100, but you need to follow the SLAM Process. And it is just not practical to do that.

To drain, you rent a sump pump from Home Depot. You need to find out what your municipality allows for drained pool water. Many of us just use our sewer cleanout.

If you are sure your CYA is just 100, then you would drain until you get 50-60% drained.

 

[mguzzy]

1. Could I live with 100 CYA? Would it just mean that I'd be adding more chlorine?

No you can't live with that. First off the CYA test maxes out at 100 so we don't really know what your CYA level is. If you have been using pucks to chlorinate then its a pretty likely your CYA is much higher. That is why you need to do a dilution test. Once we find out the actual CYA level, then we can tell how much to drain. Here is a link to the wiki CYA dilution test:

Water Testing Instructions - Further Reading

www.troublefreepool.com

And this is why you can't live with it.. the higher the CYA is the less effective the chlorine is, because it is all buffered by the high CYA. At some point you reach a point of diminishing returns, and you can't keep enough chlorine in the water for to kill anything.

Good luck!

 

[wysocki]

Yes, I did the dilution test for CYA, it came out to 50 (and x2=100). I guess I'll bite the bullet and do the drain next week. Guess I'll scrub the tiles to dump that calcium into the water first. The water has never been changed (22 years) so there's bound to be a bunch of mineral buildup. Stay tuned...

 

[Rancho Cost-a-Lotta]

Since your draining anyways, consider having your waterline scale bead blasted. Cost is about $4 per linear foot. They will need to drain water about 12". Maybe you can talk them into draining 50% + of your water while they're at it.

I used Avalon Pools, Ontario. They use glass beads and do a nice job of cleaning up. Let me know if you're interested in additional contact info.

Waterline Scale Removal - Further Reading

www.troublefreepool.com

 

[mguzzy]

That would explain the "my always-slightly-green pool". once you get your CYA down, I think you will find it much easier to manage the "slightly green" part. If you switch to liquid chlorine your CYA won't go up and you can save your pucks for when you are out of town. Do you get a lot of rain in the winter? You can use that to help manage your CYA if it drifts up.

As to the other statement in your first post.. Um.. sorry we really aren't good at compromised solutions. It kind of goes like this.. follow this procedure or deal with a slightly green pool. There is really nothing in between. It think once you get the handle on how the TFP procedure works you will be putting a lot less time managing your pool. You've been a member since 2015 so you should know this is different that what the pools stores are spouting.

 

[wysocki]

Ok, I bit the bullet and had it blasted with MaxxStrip, tiles repaired, and then drained all leaving only about 3000 gallons (10%)! Refilling it now and I realize I'm panicking about what to do next. I did a quick check of the water which is now about 1 foot from the top, and it shows no chlorine (duh) and about ph 8.0. So what to do now? I still probably have some CYA in the pool from the little I didn't flush. But how much acid & 12% chlorine to dump in now to get started?

 

[mknauss]

Chlorine is king. Add 3ppm FC worth now.

Then test all your parameters. Align them with Recommended Levels

 

[wysocki]

Last night when the pool was full, I did a quick check: TC:0 and pH: 8 so I dumped in a gallon of 12% chlorine and a gallon of acid. Ran the pump overnight.

This morning I did a full test with the TF-100:
pH: 7
FC:5
CC:0.5
TC:5.5
CH:225
TA:120
CYA:<20
I may have overdone the MA and CL a bit last night, but the numbers are quite a bit different from when I started off. The CYA is so low (I filled the tube and could still see the black dot) that maybe I should use the chlorine pucks for a while to bring it up a bit? Also, there are a few readings that aren't ideal. I've loaded the Pool Math app and entered my initial results, but I'm unclear about how one setting affects the others. So where do I start?

 

[Texas Splash]

Don't worry about the pH, it will rise back up soon enough on its own. If your spring weather is getting warm, your water could use a little more CYA. A goal of about 40 I would say. I wouldn't use pucks right now because you need the CYA to rise fairly quickly, and pucks are also acidic and your pH is already low enough. Just add about 10-15 ppm worth of stabilizer via the sock method and test again in a few days. But watch that FC. As Marty said, that's priority #1 to avoid algae. You never want it below 3 right now. In fact, you could do with a little more FC since it crashed last night and the water might be struggling. Now that you've done the water exchange and all, watch the water condition. If it gets cloudy, run an Overnight Chlorine Loss Test to see if you have excessive organics that may require a SLAM Process. If the water is crystal to the deepest past, then just stay close to theFC/CYA Levels.