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

[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!

[nefretrameses]

Woo Hoo! Congratulations! Test before adding and, in general, "sneak up" on the level you want. Add half of what you think you need and retest, repeat. Shock levels of chlorine is probably the only exception.

[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!!!

[Watermom]

For future reference, in a 17K pool, each quart of 10% bleach will add about 1.5ppm of chlorine.

[nefretrameses]

Cool, enjoy it. The pool calculator will also help out http://www.poolcalculator.com/

[Watermom]

The pool calculator is not our favorite one to recommend as it encourages people to add single large doses of things to solve problems. We prefer the test, add, retest, add more if necessary approach.