Low CYA?

[wedward]

My first water test at the Pool Store nearby on 10/29 showed:
FC - 0.05
TC - 0.05
pH - 7.9
Hardness - 263
Alk - 86
CYA - 80
Salt - 2800 (system reads 2400)

Here's about how it looked around that time:


After following their instruction, I added some Muriatic Acid (2 Cups), a bag of salt and one bag of shock/ chlorine.

11/9 Yesterday:
FC - 0.07
TC - 0.00 (combined chlor = -0.07??)
pH - 7.5
Hardness - 250
Alk - 80
CYA - 30
Salt - 3400 (system reads 2400)

Here's how it looked today (more work needed I think):


1) They said nothing of raising CYA - this is a SWG pool and according to the chart I should be near 80.Should I look to raise this? Maybe use some pucks to chlorinate since the Pool school says that is a side effect?
2) He gave me "Alkalinity Plus" (5lbs) to raise the alkaline - should I have just used Baking Soda?
3) I think my system is not accurate on the salt level or something else is off. It keeps saying 2400 ppm on the diagnostic. But each test shows a different result.

I'm in a leaf war thanks to the tree on the right side and have been cleaning up the algae and water since moving in. It's finally clear, but clearly any chlorine seems to be consumed faster than the SWG can put in. Water temp is at 65F (heater for now), so the SWG should still be producing some.

TIA for any help.

 

[mknauss]

Welcome to the forum!

This forum advocate’s pool owner water testing using a proper test kit. Order a TF100 test kit. It is properly sized for the residential pool owner.

The only other real option for a test kit is a Taylor K-2006-C. Be careful comparing prices because the K-2006 comes in sizes, designated by a letter. The basic K-2006 has .75oz bottles. You need to get the K-2006-C to get the larger bottles that you want.

I also have the SpeedStir. It makes testing much easier.

I suggest you read Pool School - ABCs of Pool Water Chemistry and consider reviewing the entire Trouble Free Pool School book.

 

[wedward]

Thanks - I have been reading and need to get my own test kit. Ordering the TF100 now. I was just confused by the local shop saying stabilizer level is OK, when CYA was so low compared to the Pool School charts.

 

[mknauss]

One, we do not trust a pool stores' results. Especially on CYA testing.

Realize that the Pool school range of CYA for a SWCG is based on science. The Pool Store does not recognize that science and do not recognize a difference between pools getting their chlorine from a SWCG or another means (liquid chlorine, etc).

- - - Updated - - -

Also, please do not use the 'Alkalinity Plus'. Return it. Your TA is actually on the high side. And the use of baking soda, IF, you need to raise TA is much cheaper.

It would be wise for you to discontinue to heat your water and use liquid chlorine to maintain your FC during winter.

 

[wedward]

Thanks - that makes sense. I'll wait until I get my testing kit to hopefully see what the true CYA is. Gonna definitely go the route of liquid chlorine to maintain in the winter as suggested. I have no idea how old the T-15 cell is, so better not run it if not needed. Just need to see whether to remove it or how to disable it. Thanks again!

 

[mknauss]

Good choice.

Take care.

 

[JamesW]

What are the first four of the cell's serial number?

 

[wedward]

The serial (I think) is 3E14220-200216 (under the barcode on the left). Would that mean 2014 was the MFG date?

 

[JamesW]

Made on Aug. 8, 2014 (Fri). Day 220 of 2014.

Is the cell a T-15?

What are the diagnostic readings?

The cell size in the diagnostic readings should match the actual cell type.

I recommend that you get a K-1766 salt test kit to check the salinity.

K-1766 Taylor Salt Test

The box salinity divided by the actual salinity will tell you how well the cell is performing.

For example, if the box reads 2,400 and the actual salinity is 3,200, the cell is performing at about 75 percent.

Once the cell drops below about 75%, it's time to consider replacing the cell.

 

[tim5055]

Thanks - I have been reading and need to get my own test kit. Ordering the TF100 now. I was just confused by the local shop saying stabilizer level is OK, when CYA was so low compared to the Pool School charts.

You don't know what the CYA level is. Unless you exchanged a huge amount of water it is impossible for the CYA to go from 80 to 30 in 10 days. Their testing faulty. But, you don't know if the first test or the second test was wrong.

 

[wedward]

We've had some pretty high levels of rain in the past weeks. Couldn't that lower CYA?

- - - Updated - - -

Made on Aug. 8, 2014 (Fri). Day 220 of 2014.

Is the cell a T-15?

Yes it's a T-15. I'll get that test kit ASAP. Thanks

 

[tim5055]

We've had some pretty high levels of rain in the past weeks. Couldn't that lower CYA?

Nope. To reduce it that much you would have to have replaced close to 8,000 gallons in your 12,000 gallon pool. Unless your neighbor is building an arc and the animals are marching down the street two by two it hasn't rained that much.

I took over my pool and found a CYA of about 250 when the pool store swore it was 80 - 90.

This is the test they get wrong the most.

I would NEVER recommend any chemistry changes based on pool store testing. So, to control your pool you need to know what is going on. Many folks have a Saturday morning ritual, dip a bottle of water out of the pool and take it to the pool store (they give you the bottle for free). They test it and sell you what they say you need to "fix" what ails your pool. But, you will find not much credence is given to pool store testing around here.

While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. Plus, the results of their "testing" is used to convince you that you need to buy things. Why do you think that testing is free?

You are looking at teh TF-100 and I agree with that kit. While entirely optional, I also have the SpeedStir and Sample Sizer. They speed testing and accuracy.