I am new to this site but looks like lots of very well informed advice! I have a gunnite pool that I had built about 5 years ago. It is in just north of NYC so has to be closed each fall. Usually there are leaves that fall onto the cover during the winter and some get under the cover. There has always been a stain each year but our pool maintenance guy has always put something in each year that has caused them to miraculously go away. This year he has tried a number of things and nothing much has worked. He advises that the stains are different this year and are due to the early and heave snowfall at the end of October last year that he believes pushed more water out of the pool than planned and resulted in the leaf debris sitting on the gunnite in some places. He has tried Jacks Blue and lately brought me a canister of ascorbic acid to try but that seems to be having only a limited effect? Here is a picture! Any thoughts, guidance would be greatly appreciated!
Leaf Stains? On Gunnite Pool
- Thread starter WB
- Start date
From the chemicals he is trying, it sounds like he believes they are metal stains. Are you using any kind of non-chlorine sanitizer like Nature 2 or Pristine Blue? Or a copper based algaecide?
Try holding a vitamin c tab (or some of the ascorbic acid) directly on the stain for a little while and see if that reduces the stain. If it does it is metals. See: http://www.troublefreepool.com/pool-school/metal stains
If it doesn't then try placing a trichlor tablet on the stain to see if it effects it. If it does it is organics.
If it doesn't then try placing a trichlor tablet on the stain to see if it effects it. If it does it is organics.
I am not sure. I will check with him and see and give both a vitamin C and a tricolor a try and report back! Thx!
Those stains sure look like leaves and sticks to me. Are these primarily (worse) above the water line or are these shots through the water? What is he using as sanitizer? White hockey pucks or liquid chlorine?
It would be interesting to see a full set of test results. I am pretty new at this BBB stuff but if the CYA were really high, the decreased effectiveness of the chlorine might not have enough effect to bleach out the organic stains. I struggled with my pool last year and I now think it was due to high CYA last year. It was all my own fault for ONLY using pucks and a floater all year.
It would be interesting to see a full set of test results. I am pretty new at this BBB stuff but if the CYA were really high, the decreased effectiveness of the chlorine might not have enough effect to bleach out the organic stains. I struggled with my pool last year and I now think it was due to high CYA last year. It was all my own fault for ONLY using pucks and a floater all year.
If it is tannins staining directly from leaves touching the pool surface, then it may eventually clear with normal chlorine levels in the pool. You could speed this process up by maintaining a slightly higher than normal FC level.
He used what he called shock twice and then he is using pucks! I believe that it was leaves and leafy water sitting against the surface! There is also a certain amount of roughness in some parts. That has also usually gone away and the pool surface is really smooth but so far this year not.
I put a Chlorine Puck on the step and it cleared the stain for an area of about 4-5 inches around it. So I think that confirms that it is an organic stain from leaves, etc... However, we tried putting an elevated level of chlorine and it has barely made a dent? Any recommendations on how to speed it up? Scrub it with chlorine pucks?
DCAG
0
WB, What do you mean by elevated levels? What was the level you tried? In pool school (link at top of page), there's a chart of the CYA/CL relationship which shows shock levels. Bring your FC up to shock level based on that chart, and keep it there.
Imagine the FC level in the vacinity of the puck which cleared up the stain... you probably didn't have the FC level high enough to affect the stains...
Dan
Imagine the FC level in the vacinity of the puck which cleared up the stain... you probably didn't have the FC level high enough to affect the stains...
Dan
Hi Dan, Thank you for your comment/question. I will check that. I wonder though, my wife thinks that taking the chlorine to a very high level will damage the gunnite? Is that likely to be the case? Thanks for your further feedback! Wm
DCAG
0
WB, Your pool surface will be fine up to shock levels. You'll need an accurate CYA level, then you can bring your CL up to shock level, and keep it there a for a few days to see if that helps fade the stains.
Check your CYA level, adjust pH to 7.2, then bring up CL to shock...
Dose regularly to keep CL at shock level for a few days.
You may also want to fill the pool up higher than normal to ensure all the stains are covered.
Dan
Check your CYA level, adjust pH to 7.2, then bring up CL to shock...
Dose regularly to keep CL at shock level for a few days.
You may also want to fill the pool up higher than normal to ensure all the stains are covered.
Dan
Thanks Dan, I am slowly making progress to figure this out. Did a CYA test and it is off the chart. Now I wonder, how do I get that down into a more normal range?
Thanks Richard! Do I need to drain 100%? Or 90% or how much? Also, I refilled it about a quarter after starting the pool up this spring. How do I know that the water that is put in it is not going to be high CYA? Thanks!
That depends entirely on what the CYA level is. There is no CYA in the water supply.WB said:
How are you testing it?
If you have the mixing bottle and view tube, dilute the water sample 50-50 with tap water, mix it, then pour that into the CYA mixing bottle and add the reagent and run the test as usual. Then double the reading, that will get you close.