Algae Growth pool chemistry seems good

[garthrob]

I have algae growth, starts in hose to pool cleaner, then spreads.

FAC 3.0
TAC 3.0
Salt 3300
CH 260
TA 100
pH 8.0, slightly high as maintenance not done for a few days , generally for most part 7.4 7.6
Acid 1
Pho 500

Pool is heated to 83 degress

Air temperature 70-85

Sunlight 9 hours

Any thoughts?

Thanks.

Garth

 

[Butterfly]

Welcome to the forum

What is the CYA level?

If you can see algae, you should SLAM the pool. Directions in Pool School. Big white button top right of each page.

Also need to thoroughly clean the pool cleaner hose, too.

Post back with any questions. Lots of folks around to help.

 

[Charlie_R]

Question for you, Garthrob--

Are those numbers from your own testing or from a pool store? What kit do you have?

 

[karmabiker]

It's very scientific around here. The cya level is usually the root problem. Don't trust the pool store tests- get one of the recommended test kits.

 

[BoDarville]

Welcome to TFP!

As others have stated, we need to know the CYA (stabilizer) level in order to conclusively determine if the current chlorine (FC) level for the pool is adequate. Forget the conventional wisdom of maintaining an FC level between 1-3 ppm. The proper FC level is dependent on the pool's CYA level as shown here: Chlorine/CYA Chart.

I'm assuming from your Salt level test results that you have a SWG pool (suggest adding pool info to signature). Even at the minimum 60 ppm CYA level that we recommend for SWG pools, an FC of 3 ppm is right at the minimum recommended level. If FC were to consistently drop below 3 ppm, that would give algae a foothold to grow. OTOH, is the CYA level is higher than that, then the 3 ppm FC itself is inadequate.

Since you currently have algae, SLAMming the pool is in order to get rid of it. There again, you still need to know the CYA level in order to dose FC to the proper SLAM level. If the CYA level is greater than 80 ppm, I would do a partial drain & refill to get it in the range of 60-80 ppm. Then you can begin the SLAM. After the SLAM process is completed, I would aim to keep the FC level at the target range shown in the chart for the pool's CYA level.

Another thought...If this pool is regularly subjected to high bather loads, you would want to dose FC slightly above the target to account for the higher than average chlorine demand that comes with high bather loads.

 

[garthrob]

Thanks for the help

I purchased TFT test kit and these are the results

FC=5.5
CC=.5
TC=6.0
Total Alkalinity=90
Calcium Hardness=440
CYA=90
Phosphates=2500 ppb
Salt=3200

Pool almost clear, algae continues to grow in pool cleaner hose.
No signs of algae anywhere else.

 

[jblizzle]

Your CYA is a little high, but workable with the SWG.

I would suggest turning off the SWG, raising the FC up to at least 20ppm with bleach, and then Perform the Overnight Chlorine Loss Test.

Since you are seeing algae and the pool is not clear, I would expect that you will fail and need to follow the SLAM Process which is going to be maintaining a FC level of 35ppm continually until you pass the 3 criteria to stop. Then you can turn the SWG back on and maintain the FC up around 6-7ppm at all times