Light Algae Growth two days after AquaRite installation

[WilmingtonF250]

Hey Everyone,

I just finished installing a new Hayward Aquarite Salt Chlorination on my in-ground pool. My chemistry is properly balanced (SI= -.01) and free chlorine = 1ppm.

After bringing my salt levels up to 3300ppm and allowing time for the salt to dissolve, I proceeded to turn the system to Auto. Everything seems to be doing fine, my chlorine has stabilized around 3ppm.

Two after after the install, I started having light algae bloom. Is this typical when switching over to a salt system? I'd really appreciate an explanation from someone. I don't understand where the algae is coming from due to my balanced chemistry... Did the salt increase my phosphates rapidly or something?

Thanks!

[Poolay]

Adding salt will not raise phosphate levels, however I suspect this is your problem. I'd test the phosphate levels and if high I'd do a phos and floc and vac to waste.

[chem geek]

What's your Cyanuric Acid (CYA) level? If it's 80 ppm, then you need to maintain a minimum Free Chlorine (FC) level of 4 ppm -- basically around 5% of the CYA level -- to prevent algae growth unless you either use a supplemental weekly algaecide (PolyQuat 60) or a phosphate remover.

If you converted to salt after previously using Trichlor tabs, then your CYA level may be very high. Is your FC level of 3 ppm lower than it used to be prior to installation of the SWG system?

[Wilmington F250]

I hadn't thought to much about Cyanuric Acid levels. They're actually a bit high (120 ppm). Does this mean I need to run the pool at 6ppm until it comes down?

I tested the water for phosphates today and they do seem to be a bit high (approx. 1000ppm) according to my test strips (deeper blue color). I've got a bottle of PhosFree on order for delivery tomorrow.

What are your recommendations Chem Geek? Thanks for the help!

[chem geek]

Yes, you either need to have your FC level set to 6 ppm until you dilute enough water to get the CYA level lower or you need to use either a supplemental algaecide or phosphate remover to control algae. The latter costs extra -- about $2-3 per week for the algaecide and a lot initially for the phosphate remover since you've got high phosphate levels. You can definitely manage with the appropriate FC/CYA ratio. I've got 2000-3000 ppb phosphates in my pool and it stays clear and great so long as I don't let the FC/CYA ratio drop too low.

With visible algae, you'll need to shock the pool to get rid of it before settling on the 6 ppm. Otherwise, you'll notice that the SWG may have a hard time keeping up. The shock level at 120 ppm CYA is around 48 ppm FC, but that's to clear a pool quickly. If you use 25 ppm FC as your target, it should get rid of the algae, and you'd add that with chlorinating liquid (you don't want to wear out the SWG since it's not good at shocking). This is why one normally does a partial drain/refill to lower the CYA level rather than try and fight algae when the CYA is high. In an SWG pool exposed to direct sunlight, a CYA level of 80 ppm usually works well.

Richard

[Pooltech32]

if you are going to shock the pool turn your SWG off until the chlorine comes down to a reasonable level, as chem geek says they don't like high high chlorine.