Initial pool test

[mbeattie]

I just got a K2006 test kit and was eager to give it a shot.

Looks like my numbers are:

pH = 7.6
TA = 230
FC = 1
CC = 0
CYA = (200+)?

So, my test tube thing doesn't appear to have a black dot on the bottom of the small tube... so I drew one with a sharpie on a white piece of plastic and put the tube on top of that. Is this valid? Or is there something special about that dot?

When I tested CYA, it was so cloudy that I couldn't see the dot after only a few drops. I repeated the test by mixing 7ml of pool water with 7ml of tap water and it still was occluded around the 100 mark. Just to be safe I did the test with plain tap water and it was easily 0. Does this mean I need to drain like 3/4 of my pool water?

The green/red alkalinity test was green until about 23 drops which seems to equate to 230 ppm. It looked like it was trying to change over before that but when I swirled it, the red went away and the green dominated. What do I need to do here? Add more acid and aerate it somehow?

Edit: FWIW, the water is perfectly clear and doesn't seem like there's any problems.

 

[duraleigh]

Does this mean I need to drain like 3/4 of my pool water?

Yes. You have no chlorine anyway (get some in there pronto) but it is largely ineffective due to the massive CYA measurement.

Get you CYA down to about 40-50 and everything suddenly gets easier.

Was that kit new? Taylor owes you a black dot view tube.

 

[mbeattie]

Is it safe to swim in like this? What's going to happen? The pool water is clear and it's been open in the sun for a few days now.

I can add a few gallons of bleach to get the FC up I guess.

 

[jblizzle]

Is it safe? Not really. The water is a not sanitized therefore you are at risk of disease transmission.

If your CYA was 200ppm, then you would need to maintain your FC above 14ppm to have the water safely sanitized.

 

[mbeattie]

So if I dump 2 gallons of bleach into it and the FC goes up to 14ish, what happens? Everyone who goes near it gets their eyes burned out?

 

[JVTrain]

With your CYA that high, even at 14 ppm, nearly all of that FC is actually bound to the CYA making it basically inert. The actual free hypochlorite/hypochlorous acid is <0.1 ppm. Much less than a pool with 0 CYA and 1 ppm FC.

 

[jblizzle]

TFP is based on understanding of the CYA/FC relationship which nearly all of the pool industry ignores.

Have you discovered Pool School yet? Start with these:
ABCs of Water Chemistry
How to Chlorinate Your Pool
FC/CYA Chart

 

[mbeattie]

I understand and am just trying to dig a bit deeper.

The issue is that I can drain water from the pool, probably. The house has a slight drainage issue but I can probably spread it out over enough time and area that it will be fine. I would have trouble refilling it though. I have a well, so the prospect of pumping 10k gallons or whatever is somewhat daunting. I would likely have to spread the fill out over multiple days/weeks. Or I can call someone to truck some water in I guess. This might be the best option.

I was considering the possibility of spreading the water replacement over more time. If I could potentially use the pool by adding extra chlorine and then replacing, say, 8 inches of water every week it spreads out the demand on the pump to something more manageable. I understand that it will cost more in bleach and probably acid but it also means my kids get to use the thing sooner.

Also, if the chemistry is so far off that there's effectively no chlorine in it, how is it not green? I mean, the water is crystal clear. This doesn't make sense to me. It's been warm, it's been in the sun... am I just lucky?

 

[jblizzle]

Yup. Lucky.

If you maintain a FC level that is at least 7.5% of the CYA level, then you will ensure it stays clear and safe.

 

[mbeattie]

Ok, so I drained the pool and had a pool filling company come today to deliver some water.

After he filled it, I let the pump run for a while (hour and a half or so) and then tested the water.

FC = 0 - eek! The water never turned pink with that powder... or maybe just a VERY light pink that was gone with 1 drop of the other stuff.
TA = 220 - I was expecting this to go down? I guess the water from their source has high alkalinity?
pH = 7.6
CYA = (drumroll...) 50

I used poolmath which told me to dump in 121 oz of 8.25% bleach to get it up to about an FC of 6, so I did that.

I'll let it circulate for another hour or two and then re-test it to make sure the FC is where it should be. Then, I should be good to go?

The TA isn't a large problem, right? It just means the pH will go up faster than if it was lower. And over time, I can lower the TA by lowering the pH and then splashing around.

 

[jblizzle]

I would be tempted to raise the FC up to at least 10ppm or so and Perform the Overnight Chlorine Loss Test just to be sure the water they delivered did not have anything in it.

BTW, You can test the FC and CC after about 30 minutes.

The TA will slowly come down as you keep the pH in range. You may find the pH is rising faster now with the high TA.

 

[mbeattie]

I will check the FC level after the sun goes down and then in the morning. The OLCT page says it should be above 3 before doing the test and I should be at 6ish so that should be good enough?

 

[jblizzle]

Well, I disagree with the 3ppm statement. A 1ppm loss starting at 3ppm is a LOT different than a 1ppm loss starting at 10-20ppm (shock level) as the OCLT was designed to be used for.

Remember that at a CYA of 50ppm. The minimum FC level (without a SWG) is 6ppm ... so you should really be dosing up to 8-9ppm to be sure it does not drop below 6ppm ... EVER!

 

[mbeattie]

The target FC is 6, the minimum is 4. Pool School - Chlorine / CYA Chart

I'll bring it up a bit to 10 ish and then do the overnight thing.

 

[jblizzle]

You are right ... I used PoolMath wrong

- - - Updated - - -

I mean ............ you passed my test of checking the numbers

 

[mbeattie]

So, I did the overnight loss test. It dropped either 0.5 or maybe 1. It's hard to tell EXACTLY when the color changed from superlight pink to clear... and I used a small sample. Either way, it should be fine?

 

[Mr Bruce]

Clear water, CC <= 0.5, OCLT <=1.0? No need to SLAM, just regular maintenance mode.

 

[mbeattie]

perfect