Pool stain help needed

[jessieejr]

I have a pool that is about 8 years old. I moved in about 5 years ago and the pool had some substantial staining or etching since I moved in. Some of it has darkened or lightened over time. I am hoping for some advice on moving forward with stain removal.

I have been lurking on TFP for about a year and have learned so much from all of the forum posters. I have been using the TF100 for the past year (I love this test kit!).

I bought one of the Jack's Magic test kits and the results are posted in the pictures below.

Current pool (Allowed chlorine to drop for the stain test kit)
FC .5
CC 1.0
PH 7.4
CH 275
TA 110
CYA 50

The first picture is representative of most of my pool surface. I assumed that the dark spots were stains or etching.



I performed the four stain tests on the top step of my pool. I am not including a picture for test 1 (the iron,cobalt&spot etching stuff) which had no affect on the stain.

Test 2 (The copper & Scale stuff)

Test 3 (O2 safe shock followed by the copper and scale stuff)

Test 4 (the copper & scale stuff followed with the iron,cobalt &spot etching stuff)

The fourth test appears to be the most effective. I was surprised that it was the white that was removed rather than the darker "spots". Is the darker color the pools original finish?

I would appreciate any and all feedback to help me understand what is happening with the pool and if I should go forward with the suggested Jacks treatment instructions.

I know the jacks magic test kit was not necessary, but I used this so that there would be no error and I could get some more specific feedback as to what happened or is happening with my pool chemistry.

 

[JoyfulNoise]

Would the fact that the O2 safe shock (which I can only assume is MPS) followed by the copper & scale removal indicate that stain is metallic in nature and possibly copper? I think the 3rd test looks more effective than the fourth one.

Did you ever try just crushing up some vitamin C tablets in a sock and resting it on a stain for 5-10mins to see what happens? Vitamin C removes iron better than copper and does nothing for organic stains. The spot etching chemicals can sometimes interfere because they could etch the underlying calcium in the plaster surface which would physically remove the metal stain along with it.

It looks like you just have a combination of really etched plaster as well as some kind of metal stain. Were metal based algaecides ever used in this pool? Does it have a heater?

 

[jessieejr]

Would the fact that the O2 safe shock (which I can only assume is MPS) followed by the copper & scale removal indicate that stain is metallic in nature and possibly copper? I think the 3rd test looks more effective than the fourth one.

Did you ever try just crushing up some vitamin C tablets in a sock and resting it on a stain for 5-10mins to see what happens? Vitamin C removes iron better than copper and does nothing for organic stains. The spot etching chemicals can sometimes interfere because they could etch the underlying calcium in the plaster surface which would physically remove the metal stain along with it.

It looks like you just have a combination of really etched plaster as well as some kind of metal stain. Were metal based algaecides ever used in this pool? Does it have a heater?

JoyfulNoise thank you for the reply.

I was unsure whether test 3 or 4 worked best.

I did try the vitamin C in the sock test with no noticeable improvement. I do not know if metal based algaecides were ever used. The pool does not have a heater.

 

[poodlegirl]

Did you ever figure out what that stain was? I have a similar stain in my pool.