Tile grout turning blue/green

[Gloryhunter]

Hello everyone. My very first post as a new pool owner.
I got the pool replastered by Pebble Sheen Aqua Blue (end of April this year) and I am already fighting some problems..
I’ve been taking care of chemicals very religiously, but I started seeing this emerging at random places around the waterline. Please can you tell me what it is?? Can't tell if it's a "growth" or some kind of deposit or if it actually turns the grout into this stuff. Many thanks in advance.

 

[bmoreswim]

Hello! Sorry you are having some trouble with your pool. We would like to see a full set of test results listed as:

FC
CC
CH
pH
TA
CYA

All of these are important to know if you have a chemistry issue. But absent that at the moment, it’s almost certainly algae. Though it could be some other startup related issue that I’m less familiar with.

For the test results though, your test kit is not sufficient. The FC isn’t the more accurate FAS/DPD version and you are missing CYA which is critical to know what your proper FC level should be per the FC/CYA Levels.

I highly recommend the TF-PRO tftestkits.net, which is a refreshed version. Also see this. Test Kits Compared

 

[Gloryhunter]

Hello! Sorry you are having some trouble with your pool. We would like to see a full set of test results listed as:

FC
CC
CH
pH
TA
CYA

All of these are important to know if you have a chemistry issue. But absent that at the moment, it’s almost certainly algae.

For the test results though, your test kit is not sufficient. The FC isn’t the more accurate FAS/DPD version and you are missing CYA which is critical to know what your proper FC level should be per the FC/CYA Levels.

I highly recommend the TF-PRO tftestkits.net, which is a refreshed version. Also see this. Test Kits Compared

Hi, thanks for the quick reply! I test the water daily, and weekly I take the sample to the store to compare. At the store they use the Lamont disc tester (i think licenced as AccuBlue system)
My current test results are:

FC: 2-3 (store 3days ago: 2.39). I usually keep this around 5, and add liquid chlorine when i see it drops. Last time added 2days ago. Today will add again.
CC: (store 3days ago 2.66)
CH: (180-195, trend from the store last 4 visits). I measured two weeks ago 200-220
pH: Today 7.9. This one I am trying to keep around 7.6, but since it is a new plaster it rises to 7.9 within two days, so i keep adding the muriatic acid.
TA: Today 90. This one is giving me headache together with pH. pH keeps rising, i keep adding acid to keep it under control, and then TA from 100 goes down below 80 within 7-10 days. Then I return TA to 110, and the whole cycle repeats.
CYA: store results from last 5 visits:52/48/48/45/43

For context, store visits were on folowing dates: 05/12 05/18 05/26 05/29 06/03

 

[Oly]

Hand spray a 25/75 solution of bleach/water on a small section of the green grout line.
You may have algae or maybe copper staining. Your FC needs to be in the target zone for your CYA and never bellow the minimum. FC/CYA Levels
Ever add any algicide solution to your pool water.?
You need proper tools, invest in a quality test kit. Test Kits Compared

 

[Gloryhunter]

Ok, so just to confirm - this kit (see photos) is not sufficiently accurate? I checked the TF-pro testkit description and it seems there is a significant overlap in chemicals used (R-0007, R-0008, R-0009, R-00010, R-00011L, R-0012, R-0013, all by Taylor in both cases). The main delta I see is for chlorine testing - is that the main deficiency of the kit I am using?

No, I never added any algicide solution. I had the chemistry started professionally by local pool store (more for having a paper trail if any plaster problems develop). And then soon after that I took over doing the chemicals myself as I was not happy how they handled the "weekly maintenance"

Thanks for the suggestion, - I will try bleach and get back with results.

 

[IceShadow]

With that kit you would just have to add a FAS-DPD chlorine test and you’d be there. The OTO test isn’t great to give you an accurate idea of your FC. The rest is the same as what comes in a recommended kit.

 

[YippeeSkippy]

Do you use pucks? Any pucks by Clorox XtraBlue?

 

[Gloryhunter]

With that kit you would just have to add a FAS-DPD chlorine test and you’d be there. The OTO test isn’t great to give you an accurate idea of your FC. The rest is the same as what comes in a recommended kit.

Thanks for clarifying! I just placed the order for FAS-DPD test. Since from the CYA/FC table i see the recommended level for me is in 6-7 range, i will just make sure to keep the OTO test in the red (5ppm+) till I get the real McCoy test.

 

[Gloryhunter]

Do you use pucks? Any pucks by Clorox XtraBlue?

No, just liquid chlorine

 

[Oly]

With your upgrade you will want to test your CC ppm. If it is in fact above 2 ppm then you will want to follow this procedure. SLAM Process The upgrade will also allow you to diagnose an algae population with this method Overnight Chlorine Loss Test

 

[Gloryhunter]

With your upgrade you will want to test your CC ppm. If it is in fact above 2 ppm then you will want to follow this procedure. SLAM Process The upgrade will also allow you to diagnose an algae population with this method Overnight Chlorine Loss Test

Thanks for guidance, I just found those pages and completed reading.
I kind of started thinking along those lines already.

A bit of background with my newly plastered pool problems (the tile grout is just one):
Within the first week of plastering (surface looked very nice and clean), while the pool company was taking care of chemistry I was doing the brushing of the whole surface twice a day. Sweeper was off for first ten days of course. However, all the dust and dirt that I was pushing to the deep end appeared to settle and stain/cause mottling appearance at the botom of the pool. No brushing or vacuming helped and I informed the company who did plastering whats going on - they said they will come back and work on it, just to wait the plaster to cure some more.
So, thats why I started logging the chemistry in detail right after that first week and been doing it for a month already. I am kind of still hoping that will clear out (if it is organic based), and been keeping the FC levels always between 3 and 5ppm. Then I noticed the tile issues I explained above. Also, along few meters on one side of the pool, tile grout started cracking - and it sounds hollow when you knock. That is definitely bad tile work, but interestingly the blue appearance of grout does not show up there. Video:

So, thats also what I brought up to the "to fix " list to my builder..

And to add - when i dive to the bottom, there is no dust residue, and I can't see any algae deposits...will try to post some photos soon..

 

[Oly]

Regarding your pH and TA issue, test your fill water. You are probably topping off your pool with tap water that has a higher TA level. Simply lowering your pH will drive your TA down overtime, but test your fill water for TA and CH.

 

[LoneWolfArcher]

With that kit you would just have to add a FAS-DPD chlorine test and you’d be there. The OTO test isn’t great to give you an accurate idea of your FC. The rest is the same as what comes in a recommended kit.

For the OP: This means that the old-fashioned chlorine test (OTO) where the water turns a shade of yellow isn't going to help you because it doesn't show the break down of Free Chlorine to Combine Chlorine. Those numbers are very important to maintaining your water chemistry. FAS-DPD chlorine testing will tell you how much FC vs. CC is in your water, and then that will dictate the actions that you take from there.

 

[LoneWolfArcher]

Thanks for clarifying! I just placed the order for FAS-DPD test. Since from the CYA/FC table i see the recommended level for me is in 6-7 range, i will just make sure to keep the OTO test in the red (5ppm+) till I get the real McCoy test.

Oops, look like you knew what Ice meant! Just wanted to be sure. When I first came to this site I had no idea the difference between OTO and FAS-DPD!

 

[LoneWolfArcher]

Thanks for clarifying! I just placed the order for FAS-DPD test. Since from the CYA/FC table i see the recommended level for me is in 6-7 range, i will just make sure to keep the OTO test in the red (5ppm+) till I get the real McCoy test.

I wouldn't be afraid to keep it slightly higher until that comes. Water is safe below SLAM levels for your CYA. Did you test CYA yourself using the kit you have? What concerns me is that the downward trend of CYA. Unless you are backwashing a filter fairly regularly or did a partial drain and fill. This is why we don't trust pool store testing.