Draining 60% water tonight, need balancing advice

[Jguderian]

All I have been battling high CYA since the moemtn I had new water last year. I think the guy who drained refilled put too much stabilizer in at start-up... I'm finding that I have to put a ton of liquid chlorine in to keep it high. Plus I'm finding that ph creeps up pretty quickly. Possibly because TA is so high? The pool gets direct sunlight from 8a-4p.

Based on pool math it suggested that I drain about 60% of the water to get back to 40ppm CYA, which I'm doing tonight. Before I add anything Id like to get some feedback on approaching a chemical balance. I don't want to fight PH

Source water:
CC: 0
TA:120
CH:0

Current pool readings:
PH:7.6 - 7.8
TA:240
CH:210 - 220
FC:8
CC:0

This is a plaster pool that had its plaster re-done about 3 years ago.

Id like to get your feedback on the correct values for each reading and which to balance first.

Thanks for your help!

-J

 

[jblizzle]

Welcome to TFP!

What is your current CYA? 40 is a little low for AZ.

 

[frustratedpoolmom]

What are you testing with?

 

[Jguderian]

Thanks! Ive been lurking for about a year.

Sorry about not including that. I wanted to be thorough on the initial post.

My CYA was/is at least 100-110. I really struggle with the black dot test.

John

 

[Jguderian]

@jblizzle Thanks! Ive been lurking for about a year

Sorry I wanted to be thorough on the initial post and forgot that key measurement.

My CYA is at least 100-110 according to the black dot test. Although its really subjective.

@frustratedpoolmom

Im using the TF-100 test kit.

 

[kimkats]

John, You need to drain some of your water. Use pool math (link at the top of this page) to see how much to drain.

Good job on having the good test kit. Please add it to your siggy so everyone that reads your posts will know what you are working with.

When you drain you can use the sprinkler to keep the sides of the pool wet while it refills.

Kim:cat:

 

[Jguderian]

Thanks Kim. I'm in the process of draining about 50-60% to get cya to 40-50. I'm really looking for the next steps and order to balance readings. I don't want to over compensate anything and create a problem for myself.

 

[jblizzle]

You need to test after filling to know what to adjust. No point in speculating now.

 

[Jguderian]

Makes sense. I just tested cya after about 25-30% drain and my cya is at 85-90. Is 40-50 appropriate for Phoenix? That's what the pool math indicates.

 

[jblizzle]

Even up to 70-80ppm would be fine with our sun. Get it somewhere around 50ish.

PoolMath is a tool to make calculations. You need to input your desired targets.

Did you drain 25-30% already and then refill and test?

 

[Jguderian]

Yeah that second result was after draining and refilling. I had the pump in all day today (9-7)for a round two and estimate I displaced about 12-15k gallons. I have a 3/4 hp pump rated for 25gpm. I'll post my test results in just a bit, but should be right around 50-60 at this point.

Stay tuned.

 

[Jguderian]

Latest results below. Should I keep trying to drain the water? Pool math says that I'd need to drain another 23% to get to 50. Based on prior results of need to drain for another 10 hours.

Cya: 65
Fc: 12 x .5 = 6
Cc: 1 x .5 = 0.5
Ch: 16 x 25 = 400
Ta: 19 x 10 = 190
Ph: 8

Let me know thoughts on a ive and whether I should take corrective action.

Thanks!

John

- - - Updated - - -

Ps - the cya is rounded up. Looked closer to 60 in the black dot test.

 

[pabeader]

Considering your location and the amount of sun you get on your pool, I would think your CYA is just fine. The only reason you might want to lower it any more would be if you plan to go on vacation and will use pucks to chlorinate while you are gone.

I would definitely get to work on lowering your pH and TA. pH first. Since TA will go down some each time you lower pH. Since you are showing a very high pH, it's possible it may take a few tries to get it down where you would like it to be. Just put the appropriate numbers into pool math and add what it shows. Wait about 30 mins, with the pump running of course, and retest the pH. If it's still high, put the new number into pool math and add what it shows.

Once you get that good, retest everything and repost your numbers.

- - - Updated - - -

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[Jguderian]

Ok I dropped the ph. Latest readings are below.

Cya: 60
Fc: 14 x .5 = 7
Cc: 1 x .5 = 0.5
Ch: 16 x 25 = 400
Ta: 16 x 10 = 160
Ph: 7.0-7.1

 

[kimkats]

How does the water look? If it is clear you can start working on bringing the TA down like this:

Pool School - Lower Total Alkalinity

A lower TA may help stabilize your PH. Every pool is different. Some like a TA of 80, some like a TA of 70. You will have to play with is some to find where your PH will stabilize.

Kim:cat:

 

[Jguderian]

Hello Kim,

The water is crystal clear. I've started bringing the Ta down. Is there a reco Ta level for my area of the country(Arizona)?

 

[pooldv]

I assume your pool is gunite and plaster? Please add sig as shown here, Pool School - Read This Before You Post

With hard water and high evaporation you need to manage your CSI to avoid scaling. Generally, you want TA between 60 and 80 to slow PH rise. Acid additions to lower PH will also lower your TA and the PH rise will slow. As low as 50 is OK if PH remains stable, if not then keep it at 60.

Poolmath will calculate your CSI for you, keep it between 0 and -0.3 for best results. I cannot emphasize how important managing your CSI is, it can add a decade to the life of your plaster. Unmanaged your plaster could fail within a few years.

More here, Pool School - Calcium Scaling
And here, Langelier and Calcite Saturation Indices (LSI and CSI)

 

[Jguderian]

I did add a signature, but posting on the phone through quick reply doesn't seem to include it. I'll update my profile when I'm back in front of the computer for the couple things I missed as the mobile app doesn't let me.

Yes this pool is plaster which was redone about 3.5 years ago. It's bright white.

I use the pool math and configure it for the tfp recommendations but it seems that guideline doesn't account for certain extremes such as arizona.

I'll work on ph/Ta today and target a Ta of 60. Being at 160 I've got a lot of work to do! The water is clear it really want to get the balance correct for easy maintenance this summer.

Thanks!

 

[jblizzle]

Make sure the box below the Quick Reply field is checked to "Show your signature".

 

[Jguderian]

Make sure the box below the Quick Reply field is checked to "Show your signature".

Will do. Completely missed the advanced options.

Quick update:

Tested PH & TA this morning after dropping PH to 7 - 7.1 last night.

PH:7.4
TA: 140

I went ahead and added enough acid to drop back down to 7, so we'll see where that gets me. Considering my TA is 120 at tap water source seems like I'm going to have a PH/TA management issue...