Circulation before Testing

[spinPHD]

Each morning before I run my test(s), I let the pool circulate for about 30 minutes. While doing so today, I started to wonder if certain test require the pool to be circulated first, while others are just as accurate with or without circulation.

Just based upon my assumption, I would guess that the FC test needs to be ran after pool is circulated since there can be hot spots.

Obviously, there needs to be circulation when adding chemicals, but when running the other tests (PH, TA, CH, CYA) do they really require the pump to run first in order to get accurate reading?

Are PH or TA different in one area of pool over the other?
Does CYA and CH accumulate at the bottom of pool?

Obviously, I can conduct my own experiment by testing both ways, but at the sake of saving reagent and out of laziness I thought some of the experts may already have insight.

Thanks

 

[JoyfulNoise]

Stagnant surface water can be a problem as it can get depleted in FC and have slight pH differences from CO2 outgassing. Probably only an inch or two before average bulk levels are reached.

I always us a 4ft draw tube (3/4" PVC with a valve on one end) to get a deep, mid-water sample and avoid any surface effects.

 

[spinPHD]

Stagnant surface water can be a problem as it can get depleted in FC and have slight pH differences from CO2 outgassing. Probably only an inch or two before average bulk levels are reached.

I always us a 4ft draw tube (3/4" PVC with a valve on one end) to get a deep, mid-water sample and avoid any surface effects.

Thats a good idea, for someone that isn't handy like myself they should sell something that lets you get sample from proper depth.

 

[Richard320]

Thats a good idea, for someone that isn't handy like myself they should sell something that lets you get sample from proper depth.

Even simpler: a 4' length of 1/2" PVC. That's what I use in the winter when the water is uncomfortably cold and I'm wearing sleeves. Shove it in, cap with thumb, lift, pivot, release into cup on pool deck.

 

[JoyfulNoise]

Make it yourself. Everything was had from ACE Hardware.

3/4" PVC SCH40 tube, 4ft long
3/4" PVC Ball valve
3/4" PVC pipe to threaded adapter
3/4" ABS hose barb
3/4" PVC end cap (optional)

All told, cost about $10-$15 in parts. Simply close valve and inset open end in pool. Open valve until water comes out the hose barb. Close valve again and lift & invert out of pool. Open valve to pour contents into sample bottle. Contents of tube exactly fills one standard Leslie's sample bottle.