Hi, I have a glass tile pool with salt system, pH and FC levels are perfect and have been since the remodel about 4 months ago. Just recently we have started to get black algae spots in the grout mostly on the bottom of the pool. I cannot use a wire brush as it will ruin the tile so have to use a poly only brush, I have just ordered Robelle 2165 3-Month Algaecide in the hopes that this might remove it. Any help would be greatly appreciated, is there a seal I can put on the grout (would mean draining the pool)?
Black Algae on glass tile pool
- Thread starter Wpatey
- Start date
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
Welcome to TFP! Good to have you here 
So are you thinking about switching over to Trouble Free Pool Care (TFPC)? If so, you came to the right place. This description is helpful (just the first two posts): TFPC for Beginners
There is no need to drain your pool, and it's unlikely that the algaecide will work.
So are you thinking about switching over to Trouble Free Pool Care (TFPC)? If so, you came to the right place. This description is helpful (just the first two posts): TFPC for Beginners
There is no need to drain your pool, and it's unlikely that the algaecide will work.
Welcome to the forum. 
Adequate chlorine will help you get rid of it. Can you post test results??
Adequate chlorine will help you get rid of it. Can you post test results??
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Welcome to TFP WpateyWe really need to know your CYA level to understand if you really have the FC at a perfect level. The Robelle 2165 contains 11% copper. Adding something with copper can cause as many problems as it solves. These include staining of pool surfaces and changing of some hair colors.
Do you have a good test kit like the TF100 or K2006 that contains fas-dpd and have you been using anything along with your SWCG as a sanitizer or for shocking ??Please add your pool and equipment info to your signature as outlined here - - > Pool School - Getting Started
Thank you all, I use the pool master test kit which has been pretty accurate in the past. The readings this morning are:
FC - 3.0
Ph - 7.6
ALK - 110
Calcium - 200
Salt - 3500
The pool is around 17000 gallons and I have has the pentair great white with brush running most days. The pump filter is cleaned weekly.
One point is being in Florida the water temp is usually high and open year round.
FC - 3.0
Ph - 7.6
ALK - 110
Calcium - 200
Salt - 3500
The pool is around 17000 gallons and I have has the pentair great white with brush running most days. The pump filter is cleaned weekly.
One point is being in Florida the water temp is usually high and open year round.
I have corrected a similar concerns in the past. Check/clean your filter first, remodels leave a mess in the pipes which gums up a cartridge filter. Add about 1/4 gallon Muriatic Acid to the water and bring the pH to 7.0 to 7.2, set your cell to boost output and bring the chlorine content to 10-15ppm. Keep the pump running 18-24 hrs day. Hold the 10-15ppm chlorine for several days while brushing the entire pool at least 1x per day. Make sure Stabilizer(CYA) is 50-70ppm. pH will increase while in generator is in boost output.
If you don't have a boost mode on your chlorine generator, you can use 3 gallons of liquid Shock to raise the chlorine levels. Just shut off the chlorine generator, follow the above steps, add Shock and then when levels return to normal turn the generator back on.
Also, because your off a fresh remodel, it may be a good idea to check the pump impeller for debris lodged in it. A small piece of debris from your remodel could have made its way in to the impeller flutes. Even if the filter pressure is good, the small debris could drop your flow rate
Furthermore, you might want to bring the calcium up to the 250-300 range if you're using regular grout. Even if water is within LSI, the water can leach calcium from the grout and could lead to future grout concerns.
Keep in mind that while an all tile pool is easier to clean, it might be a good idea to add a dose of stain prevention treatment regularly, give it a good hands on brushing and elevate the chlorine levels once in awhile. This keeps the water clean and helps to keep the pool looking great.
Sent from my XT1254 using Tapatalk
If you don't have a boost mode on your chlorine generator, you can use 3 gallons of liquid Shock to raise the chlorine levels. Just shut off the chlorine generator, follow the above steps, add Shock and then when levels return to normal turn the generator back on.
Also, because your off a fresh remodel, it may be a good idea to check the pump impeller for debris lodged in it. A small piece of debris from your remodel could have made its way in to the impeller flutes. Even if the filter pressure is good, the small debris could drop your flow rate
Furthermore, you might want to bring the calcium up to the 250-300 range if you're using regular grout. Even if water is within LSI, the water can leach calcium from the grout and could lead to future grout concerns.
Keep in mind that while an all tile pool is easier to clean, it might be a good idea to add a dose of stain prevention treatment regularly, give it a good hands on brushing and elevate the chlorine levels once in awhile. This keeps the water clean and helps to keep the pool looking great.
Sent from my XT1254 using Tapatalk
Thank you all for your feedback the CYA levels are between 60 and 80 edging closer to 60. I do have the chlorine boost and will try that (is there any damage to the cell?) along with cleaning out all the equipment.
Any recommendation on stain removers?
Any recommendation on stain removers?
There shouldn't be any damage to the cell using boost. I wouldn't go as far to use a stain remover just yet. You might try using Poolife Stain Stop or Poolife Cell Protect if it's available in your area.
Please note: Pools and cars will consume stacks of $ on a regular basis, no matter the make, model, quality or year.
Please note: Pools and cars will consume stacks of $ on a regular basis, no matter the make, model, quality or year.
Please do not go out and purchase the products recommended by LeimLife. Let us ask a few more questions to get a better idea about what is happening in your pool. 95% of the time FC levels get too low and regular algae grows and the solution for that is very simple.
We like to identify the source of the stain before we make a recommendation.
I looked up your pool test kit and I don't see the CYA test is a normal test in that kit. How did you get those results? We do not trust pool store results as they are notoriously inaccurate. Test strips are really no better than guessing. Knowing your exact CYA level is the cornerstore of pool care.
We recommended two test kits the Taylor K-2006 or the TF-100. Here is a comparison which shows the TF-100 is the best value: Pool School - Test Kits Compared
Without accurate results, you have no idea what is happening in your pool. The likely source is inadequate chlorine based on your CYA level. Pool School - Chlorine / CYA Chart
We like to identify the source of the stain before we make a recommendation.
I looked up your pool test kit and I don't see the CYA test is a normal test in that kit. How did you get those results? We do not trust pool store results as they are notoriously inaccurate. Test strips are really no better than guessing. Knowing your exact CYA level is the cornerstore of pool care.
We recommended two test kits the Taylor K-2006 or the TF-100. Here is a comparison which shows the TF-100 is the best value: Pool School - Test Kits Compared
Without accurate results, you have no idea what is happening in your pool. The likely source is inadequate chlorine based on your CYA level. Pool School - Chlorine / CYA Chart
Agreed, please don't start adding pool store chems until the issue has been positively identified. 99% of all pool problems can be solved without pool store potions.
I used a friends Taylor test kit to get the cya levels. I am not adding any more chess just boosting the chlorine with the salt generator.
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
pooldv, I think you missed the "n't" >> Agreed, please do(n't) start adding pool store chems ...
You FC is far from perfect. It's actually pretty low. Depending on where you think that CYA level is you shouldn't let the FC go below 5 and if it's at 80, then minimum of 6 and a target of 9.
CYA/FC - - > Pool School - Chlorine / CYA Chart
You FC is far from perfect. It's actually pretty low. Depending on where you think that CYA level is you shouldn't let the FC go below 5 and if it's at 80, then minimum of 6 and a target of 9.
CYA/FC - - > Pool School - Chlorine / CYA Chart
I think the 3 reading differs from what I saw on the Taylor kit, my kit only goes up to 4 so the 3 is on the high end of good for FC. This should however increase with the Chlorine boost.
You really need to invest in one of the recommended test kits because your kit doesn't work for the required level of FC. The recommended test kits include the FAS-DPD test which allows for accurate testing at very high levels of FC.
How and when did you get your CYA result? The difference between 60 and 80 is too large and we need an accurate result. Everything depends on having an accurate CYA result.
Please add your pool details to your signature as stated here: Pool School - Read This BEFORE You Post
I will invest in a good kit. The CYA reading was today, 60 was the most accurate reading.
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
The experts here will get you on track and get rid of the algae. It's not that tough and once it's done, your pool will be easy to look after. I'd like to see the tile as well.
Until you get your new kit, keep FC up at 4 (deepest pink on that tester) and your pH between 7.2 and 7.8. These are the chemicals we use: Pool School - Recommended Pool Chemicals
To get the best possible advice here, be sure to add your signature with pool details. (instructions are linked in my signature "Read Before Posting")
Until you get your new kit, keep FC up at 4 (deepest pink on that tester) and your pH between 7.2 and 7.8. These are the chemicals we use: Pool School - Recommended Pool Chemicals
To get the best possible advice here, be sure to add your signature with pool details. (instructions are linked in my signature "Read Before Posting")
Good morning all, I have been trying to upload a photo but every time, halfway through the site logs me out and it fails. Anyway black algae still persists I have increased the chlorine levels and swept the pool daily for a few days but it doesnt seem to be stopping the spread. Todays readings based on the Taylor K-2006 kit are:
FC - 4.8
PH - 7.8 (adding 46oz today to bring down to around 7.2)
ALK - 110
CH - 380 (store seemed to think this was closer to 210 which is a big difference)
CYA - 50
- - - Updated - - -
FC - 4.8
PH - 7.8 (adding 46oz today to bring down to around 7.2)
ALK - 110
CH - 380 (store seemed to think this was closer to 210 which is a big difference)
CYA - 50
- - - Updated - - -
With a CYA of 50, your SLAM level target is a FC of 20. See chlorine/cya chart here: Pool School - Chlorine / CYA Chart
Anything less and you are allowing the algae to grow and multiply faster than you are killing it. You should be testing and adjusting FC to 20 multiple times as day: Pool School - SLAM - Shock Level And Maintain
This should go pretty quickly at the water is otherwise clear. The algae got a foothold because you let the FC get to or below the minimum for your CYA.
Anything less and you are allowing the algae to grow and multiply faster than you are killing it. You should be testing and adjusting FC to 20 multiple times as day: Pool School - SLAM - Shock Level And Maintain
This should go pretty quickly at the water is otherwise clear. The algae got a foothold because you let the FC get to or below the minimum for your CYA.