Refilling my inground pool; want to get my water chemistry right

[nefretrameses]

Hey Cracker Red,

We are just down the road in DeBary. I operate my pool at CYA= 80. Follow the best guess chart and it will keep your pool sparkling. Here in Florida, higher CYA is IMHO the best way to go. I lose about 3 ppm FC per day and keep my FC=~8.0. Not an algae spore in sight. You need to stop using tabs!!! Also don't use di-chlor - both add CYA. You will have a choice between bleach, liquid chlorine or cal-hypo. Cal-hypo adds calcium, so once you know your CH measurement, Doc can advise you about that. I imagine you have an in ground gunite pool, but you should edit your signature with relevant pool info (see mine).

I was "Leslied" too (or "pool stored" as they say). Much of what they sell for water treatment can be had from Walmart, Lowes, etc. Their testing is inconsistent and inaccurate. My local store has a pretty good reputation, but they do NOT acknowledge the relationship between FC and CYA. I learned the hard way that 3 ppm of FC with a CYA of 80 or 90 will not even come close to killing algae. It takes a couple of times to really get the hang of the Taylor test kit, but once you do, you will have a great deal of confidence in the numbers. You will "learn" your pool in no time flat.

In the evening my wife asks me if I'm "pool blogging" again. And I say yes. It's amazing how many times the same advice is offered from the Moderators, and when followed, solves the problem. People are amazed!

There's lots here to learn and it's pretty well organized and searchable so you can find out about different aspects of you chemistry, plus.

John

[Cracker Red]

CYA test with the K2006 was off the scale. I had drained 12" of water from the pool, and refilled today while running the pump.





Learned today that the PO had set the pool pump up to only run 4 hours a day.

Also....in the myriad of valves and plumbing by the pump there is a valve which is troubling me. It says "Skimmer" and "Drain".

The bottom of the pool has what appears to be a drain (about the same size hole as the skimmer basket) but it has a cover screwed down over it. If I turn the lever on the valve from skimmer to favor the drain side, the pump starts cavitating quite a bit.

Could the drain be capped off? And why the heck would you do that? I want to dive in the pool and unscrew it, but I'm a bit apprehensive.....why would someone cap off the drain in the bottom of the pool ?!?!?


Algae is getting worse. Came home with 2 gallons of 8% bleach from Lowes. Should I dump one/both in tonight?

[Cracker Red]

Please forgive my error....the main drain isn't capped....the drain cap just appears that way from above. It's just a slightly raised lid. After screwing around with the valves I've figured out I can use the main drain, the skimmer, or a combo of the 2. I can also adjust the amount of vac that creepy uses (Baracuda 3?). So the main drain works, which makes brushing and cleaning this thing up a bit easier.

Let me throw another question at you, in addition to my messed up chemistry. If the pool guys have been using tri-chlor tabs for a long time, and not adjusting the PH.....could this be why I have some "thin" spots on the marcite here and there?

Thank goodness I found this place/forum!

[PoolDoc]

17K gallons? Dump BOTH gallons of bleach in, and then some. Did you get the local OTO kit? With the CYA reading your picture shows (~150 ppm), you'll need to get at or near OTO "orange" to start getting your algae under control.

And yes, if you're pool has been run at low pH for a long time (which tends to happen with trichlor use), that would lead to rough and thin plaster.

Post your COMPLETE test results on the refilled pool. But, when testing the CYA, test a mix of 1/2 pool water and 1/2 tap water. Multiply the result by 2.

[nefretrameses]

OK, so the CYA test is the most difficult because it's not a color change, but a disappearing dot. If you haven't done so, go to the Taylor website and view the demo videos for this kit. Mix the CYA test solution and shake for a good minute. Let it sit while you do your other tests. Hold the vial at your waistline facing the sun. The dot must disappear completely from view. You can pour the sample back into the mixing bottle, shake again for a few seconds an repeat the test. f you did this, mix your pool water with DISTILLED water 50/50 and repeat the test. Multiply your result by 2. This is MOST IMPORTANT to control algae since the amount of FC you need to fight it is directly dependant on CYA

If you have CYA > 100 and algae I would raise FC to shock level in the best guess table (25 ppm for CYA>100) and keep it there consistently throughout the day until the water clears up or you get other advice from Doc. If this algae easily brushes up into a fine powdery cloud and mostly is on the shady side of the pool, it may be mustard algae and you should use the shock+ levels. Run you pump 24/7. 4 hours is OK in winter, but I generally run my pump 8 or 9 hours in summer.

Don't panic and add any crap from Leslie's without Doc's OK (or one of the other Mods). They often contain copper or other metals that clear up algae, but will cause other problems afterwards (stains, green hair, high chlorine demand, etc.)

You did not post the results of the other tests: FC, PH, TA and CH. These things can affect your finish. See my thread "Sand in the bottom of my pool". In particular, low Ph will cause damage. Raise Ph with 20 Mule Team Borax from Walmart's laundry aisle. If your Ph is 7.2 or less you should do this NOW.

So:
1. Raise FC to shock levels and keep it there.
2. Run your pump 24/7.
3. Test again and post results.
4. Adjust Ph if less than =7.2.
4. Use POPP (Pool Owner's Patience & Persistence)

Check your Ph before raising to shock levels. High FC (like >10ppm) can make the Ph test read high.

Marcite - Are they thin spots or stains do you think? Consistently low Ph ( like off the scale low) could do this. Are the spots near a return? Doc may want to move the finish issue to another thread.

Main drain. How old is the pool? A main drain may have been plugged and abandoned if there is a leak in that line. You said the pump cavitated, which results from trying to draw water from a closed pipe. Could it have just been air in the line that had to clear? Sounds like it, since it's now working. Monitor your water levels for an unusual or excessive drop beyond evaporation (which can be significant around here).

Hang tough, you'll get it, then it's easy. My pool never looked better since coming here.

According to the pool calculator (www.poolcalculator.com) you need 264 oz. of 8% bleach to raise FC by 10 ppm in you 17,000 gal. Pool. Thats 528 oz. To get 20 ppm. (4+gallons). Algae killing will use up chlorine, so you have to stay on top of it and not let FC drop during the fight.

Gallon calculation for a pool are notoriously wrong. You pretty sure about the 17,000?

John

[Cracker Red]

Sorry for the delay....been stupid busy all day with house stuff.

I found a few things that might help? forgot I had this, but picked up a 3 gallon jug of 10% chlorine the other day for the house water system. It doesn't need any at the moment, so I'm assuming I could use that?

Also found a packet of "Power Powder Plus" - label says 73% Calcium Hypochlorite.....minimum 70% chlorine and as best I can find online it doesn't have any stabilizer in it.

My test results are puzzling to me. It appears as though my CYA has actually risen ?!? I've added nothing to the pool other than the generic 8% bleach since we began this dialogue. It's been raining on and off today, little to no sun.

My CYA level measured out to be just above 100.....with the half solution !?! The full strength test showed the amount of solution to see the dot to be less/high test result.....but off the scale.
PH 7.6
Alkalinity 130
Calcium 320

FC .2ppm



Should I get the hose out and start draining like half the water?!? Or add the chlorine and shock that I have now? The algae that is on the bottom is as you describe it above.....brushes up easily and clouds.

==============================

Just read more on the CYA test.....I've been doing it on the dark counter top in the kitchen. Holding it up with an ample amount of light to see I get 80 with the half test so 160. Coincides with Ben's estimate of ~150 (what...you've done this before ? )

Sorry for the quick follow up post....I just was eager to post the results without studying the test procedure adequately.

I'm assuming I continue with my course of action - chlorinate!

[nefretrameses]

FC = 0.2 ppm is way low. Add bleach or liquid chlorine to get to 20 - 25 ppm and keep it there consistently until your pool is clear. See the best guess chart. The other measures seem OK for now. Don't use the Power powder it's cal-hypo and will add more calcium that you do not need - no stabilizer in it though.

I think Doc would agree - the first priority is to kill the algae and get the water clear.

Doc suggested an OTO test kit and keeping chlorine in the orange. It's cheap to test this way, since you should be testing and adding chlorine several times a day during the fight - even (or especially) in the rain. Of course you can use your Taylor kit. Use the 10 ml sample (0.5 ppm per drop). Also, you only need one scoop of the powder for either the 10 or 25 ml sample.

Wait for Doc before draining. If you are refilling from a well, you will have iron in the water. It may be necessary to know how much. Metals and high chlorine usually = stains. You may already have a filter on your well for this if you are using it domestically.

If the algae is not more noticeable on the part of the pool that is most in the shade, meaning side walls, it's probably green algae (shock level in Best Guess). If it is on the "shady walls" it may be mustard/yellow algae (+shock+ in BG). But you're not going to kill anything at 0.2 or even 10 ppm.

[Cracker Red]

Learned a few things over the past day.

Always test your water before adding

Rained nearly 9" in 30 mins yesterday. Had to drain the pool down....then left the thing draining on accident and drained out quite a bit of water. What I'm left with is hopefully an improvement.

CYA 90
FC 16 ppm

Water looks great!

[PoolDoc]

Sounds good!

[Cracker Red]

Just wanted to check in and say thank you!

Pool has never been better.

FC is now 8
CYA is 85

No algae, water is crystal clear.

I do have a question while I'm thinking about it..... approx how much chlorine (10%) will I need to add to raise my FC by 5? Given the pool is 17000 gallons. Just wondering if there is an approx amount to start with so I don't spike it high out of the safe to swim zone.

Thanks again!!!