Should I Drain the Pool (from new pool owner)

[Zenghaidong]

Another test at 7pm
FC: 8
CC: 0.5
Add chlorine to bring FC to 16.
Busy on work and kids' preparation for school, wait too long to do this test.

Last night at around 9pm, I tested the FC to be 14.
This morning, I tested it to be 13.5 with CC at 0.5.
I guess it passed the OCLT.
So I let the chlorine level drop down to 8ppm at around 6pm (still higher than recommend level, so no LC tonight).

 

[mknauss]

Did you pass all three criteria?

 

[red-beard]

You are in Houston, may I ask why you drain/refill the pool every year?

It wasn't planned - Here is why - I've had a terrible mustard algae issue for YEARS. I lurked here for many years before joining. I knew I had reached stabilizer lock. But I still used the Trichlor tablets.

2014 - CYA probably around 1000 PPM (7 years Trichlor)
2017 - CYA too high (3 years TriChlor)
2019 - CYA Too high and we had a dead possum (Mrs. Beard said she would not swim unless I changed water)
2020 - CYA Too high - I had started to follow TFP methods in 2019, but wanted to "use up" my Trichlor and overshot my CYA.

This year (2020) after refilling, I nailed my CYA level and have followed the TFP methodology. You have to have the right test kit. And since, I've added a pH meter to make that reading quicker and easier. And surprisingly, the Speedstir really helps make the tests more accurate and faster. And No mustard algae!

 

[Zenghaidong]

Did you pass all three criteria?

I think so.
CC is always less than 0.5 during the process.
Overnight FC loss is 0.5 ppm.
Water is clear and no visible algae.

 

[Zenghaidong]

It wasn't planned - Here is why - I've had a terrible mustard algae issue for YEARS. I lurked here for many years before joining. I knew I had reached stabilizer lock. But I still used the Trichlor tablets.

2014 - CYA probably around 1000 PPM (7 years Trichlor)
2017 - CYA too high (3 years TriChlor)
2019 - CYA Too high and we had a dead possum (Mrs. Beard said she would not swim unless I changed water)
2020 - CYA Too high - I had started to follow TFP methods in 2019, but wanted to "use up" my Trichlor and overshot my CYA.

This year (2020) after refilling, I nailed my CYA level and have followed the TFP methodology. You have to have the right test kit. And since, I've added a pH meter to make that reading quicker and easier. And surprisingly, the Speedstir really helps make the tests more accurate and faster. And No mustard algae!

Wow, what a history!
I am glad you finally got it under controlled.

 

[red-beard]

Wow, what a history! I am glad you finally got it under controlled.

I'm so happy with my pool I have spent more time in it this year than any year I remember!

 

[Zenghaidong]

I think so.
CC is always less than 0.5 during the process.
Overnight FC loss is 0.5 ppm.
Water is clear and no visible algae.

This morning, I did the weekly test:
FC: 3.5
CC: 0
PH: 7.5
TA: 60
CH: 250
CyA: 30

It is really hard to draw a clear line on the CyA test, in around 30, I still can barely see the black dot, so I am not quite sure about the result, but I am confident it is between 20 and 40. Should I add some CyA to bring it up to 30-50? I came from high CyA, so I actually want to keep it low so I have some margin when I am out of town in the future.
What chemistry do you guys use when you are out of town and don't want to bother neighbor to add liquid chlorine?
I am at the low end of CH, should I bring it to 350 or so?

Thanks!

 

[red-beard]

Those numbers look great! The CH is inside the acceptable range, but you could go higher. You might consider use Calcium Hypo Chlorite to chlorinate and add Calcium. Zappit 73 is about $150 for 50 lbs online. In my pool 50 lbs of CH73 will increase my CH by about 125 ppm. For you, 50 lbs (over a life of the canister) would add about 220 ppm CH. Your CSI is -0.16, which is fine. If you let your pH drift up a bit (do nothing, it will raise on it's own!), the CSI will improve. I let my pool go to 7.9 and then dose with muriatic acid to drop it to 7.6-7.7.

If you plan to go to bleach (liquid chlorine), you might get some of the Calcium raising supplement to raise it to 350, which would raise your CSI to -0.05. OTOH, running 7.7 pH with 250 will make your CSI 0.02, or almost PERFECT. it is all a balance. I like to use the "old" pool math website, ( PoolMath ) for these types of "what if", because you can make tweaks and see the effects. I use the "new" pool math app for my logs and additions.

Some here would suggest a higher CYA. I'm running 30 CYA right now. If the ChemGeek charts are correct, 40 CYA will only reduce sun-losses by 5%. Most see more sun-loss reduction than this. With my Mustard algae issues, I decided a lower CYA was better. With 30 CYA, I raise my FC to 6 every evening. With my Mustard Algae issues, I started the season with 8 FC every night. But I reduced it to 6 and I haven't had an issue in the 3 months since I drained and refilled my pool.

 

[red-beard]

What chemistry do you guys use when you are out of town and don't want to bother neighbor to add liquid chlorine?

This last trip, my CYA was down a bit from rain and sun-losses. First I added a bunch (2 gallons) of liquid bleach. I then put 6 Trichlor tablets (3 lbs) in a skimmer (I run my pump 24/7 so this is not an issue, but a floating feeder would be better). They take about 4 days to dissolve, which meant I was adding 12 oz per day. It also added about 8 ppm CYA, which was fine as I needed some. When I returned on the 5th day, my FC was 9. Over is better than under.

On the 4th day, since I was delayed going home, I had a neighbor add 4 slow dissolve Cal-Hypo tablets. These don't add CYA, but do add a small amount of CH. They are EXPENSIVE, 10 lbs for about $65. (Amazon.com : Poolife NST Tablets (10 lb) : Garden & Outdoor), but are an easy way to add chlorine without CYA. They are "messier", as they become "sticky" while dissolving. Much better in a feeder than a skimmer, especially if someone needs to dump the skimmers. They make a mess on the pool deck.

 

[red-beard]

Continued

I have always thought there must be a way to drill a hole in the bottom of a 5 gallon plastic bucket, and install a metering valve. You adjust the valve to a certain number of drips per minute for your chlorine addition. You then pull a skimmer lid and put the 5 gallon bucket over the skimmer opening. If I need to increase my FC by 3 ppm/day, I need about 3 liters of 10% bleach. This approach would last about 7 days, before someone needs to refill the bucket.

3 liters = 3000 ml = 60000 drips. This is about 42 drips per minute, or 1 about every 1.5 seconds. I would test it with the bucket 1/2 full with water. A full bucket will have higher head and drip faster while a near empty one will drip slower.

My biggest concern with this red neck engineering is that something could knock the bucket over...

 

[red-beard]

Continued

And this is the reason most of the people here have switched to Salt Water pools with a Salt Water Chlorine Generator. Continuous Chlorine production. Mine is just about ready to install!

 

[mguzzy]

A full bucket will have higher head and drip faster while a near empty one will drip slower.

Use a siphon and the drip rate is constant... or use pucks while you are away.. or if you travel a lot, put in an SWG..