Green Pool.....Huh?

Oct 18, 2013
4
Okay guys here's the issue; 12 inches of rain in 12 hours, a third acre of green grass run-off rolled into my pool for several hours... Pool specifics; 19 thousand, in-ground pebble tech plaster, pentair 520 cartridge filter system... When I got home the pool was dark and muddy... To preface this; this happened about 3 months ago, but to a lesser degree. Pool was still dark and muddy. I ran the pump for 48 hours straight and the pool became crystal clear... Now to get back to my question, with the dark and murky water, I've been running the pump for 5 days. The water chemistry is perfect, the pool sides and bottom scrubbed and vacuumed, and a water analysis taken to the local pool store and found to be optimum. However the pool has a tint of green to it. My question is; is it possible that the grass run-off has died my water a shade of green?
 
Welcome to TFP!

Pool stores know so little about water chemistry they are a waste of money even for the free testing. Dollars to donuts your chlorine is too low for the CYA level you have, but no way to tell without actual test results.
 
Welcome to the forum Pilot!

Your green is most likely algae and not grass. You will find we put little faith in Pool Store numbers here. When you say "perfect" we still want to see specifics. Can you post a list of the results they gave you? We encourage knowledge and controlling your own pool by testing and understanding some basic pool chemistry. If this is something you are interested in doing, we love to help.
 
The green has NOT subsided at all... It's been over a week: Here are the numbers (as have been for the last 5 days or so:
Free Chlorine - 3 ppm
Total Chlorine - 3 ppm
Calcium Hardness - 260 ppm
CYA - 72 PPM
Total Alkalinity - 90
Ph - 7.6
Copper - 0
Iron - 0
Total dissolved solids - 0
Phosphates - 90 PPB

As a family that has been around pools for many decades, I am amiss to what has happened - My pool is a very pretty "bright green" and smells odorless and is crystal clear - Minus the pretty tint of bright green!! HELP!!!
 
If your pool is a clear green and not a murky green, the most common cause of that is iron precipitation.

When you were cleaning it, did you give it a pretty big dose of chlorine? Often that is the trigger.

I see your pool does not test positive for iron but we have learned that iron can still be in precipitate form in your pool regardless of the test.

The solution for that situation is time. Keep your FC around 4-5 ppm and run the filter 24/7 The iron should slowly either get filtered out in your filter or re-dissolve back into solution.
 
If it is truly iron and isn't going away, then a metal sequestrant may help, but it would be better to try and remove it completely. However, I'm not convinced this green is actually iron (that's usually more yellow, but might look green against a blue pool surface). If you lowered the pH and the color lightened up, then that would be an indicator of it being a metal.

Also, your FC is too low for your CYA level, but since it's from pool store numbers who knows what is really going on. You really need to get your own proper test kit, otherwise you are shooting in the dark.
 
So, if it is not Iron... Could it be dye? If it is not dye, What could it be? I took a two gallon sample and super duper chlorinated it to see if it was algae.. approx (150 PPM) The color did not change..Hmm... It's not algae I presume.
 

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zea3 said:
By any chance do you use any fertilizers or other chemicals in your yard?
That was my thought, too. Lots of lawn fertilizers have iron compounds, and a lot of runoff will bring it with it.

On the other hand, I don't trust pool store testing; 72 CYA is a little too precise if you ask me. But if it's even close, then FC is too low.
 
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