Unidentified Pool Stain (organic?)

[BigKid4Life]

Hi - We're new to pools and have loved all of the resources on TFP. We're in the process of weaning off of the "pool guy" and maintaining our pool ourselves but we aren't there yet.

We've been seeing a few brown spots showing up on the bottom of the pool and we can't figure out how to get rid of them (current theory is that they are some type of organic stain as we have Deodar Cedar & Zelcova that add debris to the pool). The combo nylon/stainless brush isn't doing a thing and the chlorine doesn't seem to be working. We have these in about 7 or 8 places scattered around the pool. Any idea what we should try to get rid of thesee?

We need to better understand our CYA...I'm suspicious that it's higher than 110 and wondering if this renders our chlorine useless at helping break down these stains (if organic).

Any help would be appreciated!

pH: 7.6
FC: 7ppm
CC: 0ppm
TA: 90ppm
CH: 190ppm
CYA: approx 110

 

[ajw22]

You say your CYA is around 100. Did you do a 50% dilution test?

CYA > 90 dilution Test
For CYA > 90ppm, repeat the test adjusting the procedure as follows:

1. Fill the mixing bottle to the lower mark with pool water.
2. Continue filling the mixing bottle to the upper mark with tap water.
3. Shake briefly to mix.
4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.
5. Continue the test normally from adding R-0013, but multiply the final result by two.

Your FC needs to be 11-13 or more with CYA over 100. 7 is too low. See FC/CYA Levels

For your stains follow the TFP stain identification process...

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

 

[BigKid4Life]

I tried the tri-chlor and the vitamin C and didn't see much change. The vitamic c did appear to fade the quartz a bit so I have a slightly lighter spot where I tried that treatment.

I ran the CYA test 4 times with the dilution both 2:1 and 3:1 to compare results and got results consistently around 180ppm (I'm sure it's no surprise higher than our pool guy said). Also invested in 16oz bottle of the reagent

CYA 180
FC 7
PH 7.8
TA 90ppm
CH 190

Given how high the CYA is - should we throw out the 2 tri-chlor pucks we have in the floaters? Given our evaporation in NorCal (currently 102) I'm adding water regularly and hope that with the water added daily and the rain which will eventually show up we can get CYA down with draining.

Should we start increasing FC now a little bit each day? I would personally feel better troubleshooting the stain if I new we've been running at reasonable FC levels for a few weeks. Given the test results I doubt our FC is doing much if anything at the moment.

 

[ajw22]

FC of 7 is doing little good with a CYA of 180. You need a FC of around 20-22 which is really unmanageable. Your pH testing will not be accurate with that FC level.

You really have to drain 75% of your water and get your CYA down to the 40-50 range. Adding water does hot change the CYA level if the water lost was due to evaporation. The water evaporates but the CYA stays in the water.

You need to stop using Trichlor and chlorinate using liquid chlorine or a SWG.

Read about our No Drain Water Exchange Process.

 

[BigKid4Life]

thx Allen.
Is it likely those brown spots are organic not disappearing because the FC is useless?
Also - what's the downside of maintaining FC of 20? just too much hassle constantly adding chlorine or is this level actually a problem?

 

[ajw22]

Hard to say about your spots. I would get decent water chemistry then tackle the spots.

It will take a lot of chlorine to maintain a FC of 20 and you will not have a reliable way of checking your pH.

 

[BigKid4Life]

water exchange it is.
18 units of water at roughly $8/unit is a heck of a lot cheaper than RO or throwing too many chemicals at the solution.

thx again for all of your input.

 

[duraleigh]

The "stains" look like pelletized fertilizer dropped in the pool but that's a guess. As ajw22 suggests, fix you water first, then work on the stains