1st time pool owner - Water crystal clear but numbers off

[vcarnett]

Hello, I' trying to figure this out on my own but still not quite sure where to start after all the reading. I was fooling myself thinking that the chemistry must be correct since the water is crystal clear. Then I found TFP and purchased a Taylor k-2006. Please see my pool characteristics in my sig.. I don't want to do anything until I've confirmed with the experts here.

My readings today: Note: we've had LOTS of rain over the past couple of weeks and the water is a good inch high (I had to plug my drain due to problems)
pH - below scale - I'm thinking ~6.9
TA - ~50ppm (added 5 drops r-0009 before desired level reached)
Calcium - seems OK. Albeit at the high mark of 400
cya - below the indicator (seems to be around 130-140)
FC was off the charts. I'm sure this is not accurate since the chem is off.

If my understanding is correct I need to get cya in balance and then work from there?

Thanks!
Vince - Austin TX

 

[jblizzle]

Welcome to TFP!!!

If you have the K-2006, it does not appear that you did the FAS-DPD chlorine test ... since there is no "off the charts" for FC. You sure you did not buy the K-2005?

Really the first step with a CYA that high would be to replace half the water to lower the CYA, then test it again and see if you need to replace more water.

 

[JVTrain]

If your CYA is high but your chlorine is also high, that's the only reason you don't have a visible algae problem already. Many people have high CYA but are maintaining low FC levels... which leads to algae.

FC "off the charts"? It may take a lot of drops but you can get there with a FAS-DPD chlorine test. Use a 10 mL sample volume to save reagent.

High FC (above 10) invalidates the pH test. However, usually when you have high FC and try the pH test, it reads falsely high pH, not low.

One thing you can do now is dilute your pool water 1:1 with tap water and redo the CYA test. That's the only way to get an accurate number above 100. Based on this number, you'll know how much of the pool water you'll need to replace to get your CYA in a manageable range.

 

[vcarnett]

Thank you! I just posted again as I hadn't yet seen this reply. Here's what I posted (a little more info. Sorry, I did the FAS-DPD but didn't list as I thought it was not correct. I did the 25ml samp and had to add ~85 drops, so ~17ppm? OK, so I'm hearing that I need to replace much of the water. Will do.

Another question: I keep 3, 3" Chlorine tabs (Leslie's jumbo 99% trichloro-triaz, 90% available chlorine) in both my return skimmers. Is this OK?

Readings

FC 17ppm (~85 drops r-0871)

pH: had to add 9 drops Base Demand reagent (r-0006). Table suggests adding ~4lbs Soda Ash (17k IG pool)?

TA: 5 drops r-0009 (~50ppm)

Calc: Seems OK. Albeit on the high side of good @ 400ppm

cya: Dot disappeared below indicators. I'm estimating 130 - 140 ppm (seems odd given that the water is clear)

CC = 0

Note: we've had LOTS of rain in the past couple of weeks and the water level is ~ 1" high (I had to cap my drain due to a problem. I was hoping to keep it high since evaporation (usually) is rapid.

Thanks!!

 

[borjis]

stop using the tabs...thats contributing to your CYA.

just use bleach.

wait until your fc is below 10 for an accurate ph test.

 

[jblizzle]

Another question: I keep 3, 3" Chlorine tabs (Leslie's jumbo 99% trichloro-triaz, 90% available chlorine) in both my return skimmers. Is this OK?

No it is not OK and is in fact the reason your CYA is too high and you have to replace water. And your CYA is likely much higher than you think because the test scale is logarithmic.

Have you discovered Pool School yet? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool

 

[vcarnett]

OK got it. I will replace some water and ditch the tabs. Thanks so much for the help!