Starting from (near) Scratch

[mettius]

I've had my pool for a few years now (~6). Long and the short of it, is I've been using a combination of Trichlor tabs (because, lazy) and Lithium Hypo for superchlorination/shock (so as to not build up the CYA level too quickly).

I live in central Texas and we don't close the pool. But I pay a whole lot less attention to it out of season. I'm likely to check the chemicals about once/month in the off season. Typically all that gets done is to adjust the PH (down).

I'm "opening" the pool now, and drained off somewhere between 2/3rds and 3/4 of the water because the CYA level was off the scale of my test kit (it maxes out at 120. So I estimate it was somewhere in the 150-160 ppm range). Pool went green last week. I noticed it last weekend and took FC up to 12ppm with the lith hypo. (I ran out of the R-0013 to test the CYA, or I'd not have bothered seeing as how high it was). Pressure was running super high (30 or so) so I back washed and that took it back down to <10psi. I know I've been filtering a lot of algae and figure it is time to pull and clean the cartridges, but that will have to wait until the weekend.

Anyway, I'd like to get off to a good start. And I'm ready to swear off the Trichlor tabs other than to add CYA, or for being out of town on vacation.
Pool should be back up to proper levels in about an hour. What should I do next? Adjust TA, PH? I'd like to do things right this time.

Pool is 20,000 gal, Pentair Intelliflow VS, Quad DE 60 filter,
I intend to use the lith hypo for chlorination (I don't like dealing with liquid chlorine).

Regards,

 

[Texas Splash]

Hello! Like you, our pool is open year-round. As such, it gets fed a steady diet of HEB's regular Bravo bleach each day. Wal-Mart's Great Value is just as good. To clear that pool of algae, you'll need to perform a "SLAM" (link below). To perform a SLAM, you must know your current CYA to ensure you increase the FC to the correct level. Without the CYA, everything is guessing. So that would be priority #1.

Do you have the FAS-DPD (powder & drop) testing for FC? That's a must as well as the required SLAM FC level could be anywhere from 12 - 28 or more based on your CYA (Chlorine/CYA Chart - link below).

So what to do now? Get the R-0013 reagent and confirm the CYA as soon as you can. Lower pH to 7.2. Once CYA is confirmed, adjust FC to the proper SLAM level and do the TFP SLAM. You mentioned you don't care much for liquid chlorine, but it's really the best way to do the SLAM, and certainly more cost effective.

Hope that helps get you going. Let us know if you have any other questions.

 

[mettius]

I swear I posted a reply to this with my water stats last night...

Here goes again.
Water Temp 74 deg F
FC 0.0
pH 8.0+ (Higher than 8.0)
TA 130
CH 240
CYA 42

Last night I added 22 fl oz of lith hypo to bring FC to 3.0
Today after work I added 38 fl oz of Dry Acid to lower pH.
Prior to adding the Acid, I measured FC, it was at 1.4.
Will add more Lith Hypo after an hour to bring this back to 3.0

Unfortunately I have three pucks of Triclhor in the autofeeder, which I can't get out. So I lowered the dial on it as low as it would go. Guess I didn't drain enough water, since I still have 42ppm CYA. From what I've read here each of those three pucks are going to add 1.7ppm CYA each taking me up close to 50, which I'm guessing is getting too high?

If I'm going to be using Lith Hypo daily (vs bleach) to replenish FC, what CYA level do I want?

 

[Texas Splash]

It doesn't matter which type of chlorine (litho, bleach, cal-hypo, etc) you use to reach an FC level as long as you get to it. Of course there are side effects with some, but we usually know that before hand. Your biggest issue right now is I don't think you'll reach the required FC SLAM/Shock level to properly remove the algae. With a CYA approaching 50, it's normally okay for TX summers in a clean pool, but when you have to remove algae, the FC level needs to be "20". That's why bleach is such a good product for a SLAM.

Certainly your call if you prefer to use Litho, dry acid, etc. But if you have any questions about the proper levels to be at, please see the "Recommended Levels" link below in my signature. Maybe that will help you.

 

[mettius]

I don't have any visible algae anymore, but I can get onboard with the need to SLAM to be sure. Guess I'll go buy a couple gallons of Liquid Chlorine tomorrow and start the process.