Pool store testing vs noob testing

[BasicTek]

Hi all.

I've recently started testing my pool myself (last couple weeks) with a Taylor K-20006C purchased in November 2016.

My last #'s this morning are...

FC 13 (to note I've been running for over 30 hours with my SWCG powered off trying to drop my FC down near single digits)
CC 0
PH 7.4 (to note I'm putting in 20-30 OZ muriatic acid a week to maintain this since switching to SWCG in an 11K gallon pool)
TA 110
CYA 160 (with 50% dilluted) I was seeing up to 200 a week or so ago but I've had about 1000 gallons replaced by evaporation, (and I drained a little) we just had a couple days of rain last week

Now I've compared results with the pool store repeatedly and I'm constantly seeing much higher readings of FC and CYA myself. I don't have a lot of confidence since I started testing 2 weeks ago and they (at least the owner) has been doing it for 30 years.

The owner has come up with the following results

FC 10
CC 0
PH 7.4
TA 100
CYA 100 (full test) - since they were at 100 I asked him to do a 50% dilluted test and he got 100 - 120

Since the CYA is considered much more of a factor here I'm curious could the difference be due to my testing ability? Are there any noobish mistakes people make? Maybe my eyesight is not black dot friendly??? Any ideas would be much appreciated...


Thanks! - Tim

 

[Donldson]

Are there any noobish mistakes people make?

Yep, going back to the pool store to "verify" your numbers and then second guessing your results. Big rookie mistake that almost all new people make. If pool store numbers were reliable we wouldn't have insisted you do your own testing, now would we?

Also, evaporation doesn't reduce CYA. The differences you are running in to are mostly due to the increased margin of error when you do a diluted test. you should really do something about that.

 

[duraleigh]

A prime tenant of TFP is "Trust your own testing".

I don't see anything that stands out as a test error on your part.. He may not be able to test above 10 FC if he is only using a DPD test.

I'll take your results every time and would bet money on you being right.

Now, you need to get that CYA down. That is simply too high to correctly manage your pool.