Powdery Sediment On Bottom Of Swimming Pool..Yellow Algae..

by Brad
(Riverdale, GA)

After having my water analyzed I added soda ash, then alkalinity up and finally Phosfree. I ran the pump for 48 hours and the water turned cloudy.

We turned off the pump and after a day, the pool cleared with a powdery yellow sediment on the bottom.

Is this yellow algae? I have never used Phosfree before. The pool clerk could not explain/ understand what happened. Can you?

Thanks

Thanks for the question Brad

First I would say that using different chemicals to raise your pool pH level and total alkalinity might be a waste of money. One of the best chemicals (if you can call it that) would be sodium bicarbonate, or normal baking soda. You can use this to raise both your pH level and alkalinity.

Many people have had very good success with 20 Mule Team Borax to raise the pH level and that doesn't affect the total alkalinity very much.

Swimming Pool pH Levels..Chemistry..Alkalinity..Water..Care

Swimming Pool Alkalinity..Adjusting Your Pool Chemistry..Water Balance

Next is to get a Taylor Reagent FAS-DPD K-2006 pool water test kit. This is the kit most pool professionals use and it's the most accurate.

Water Testing Kit..FAQ..Chemistry Testing..Procedures..Balance..Swimming..

As for Phosfree, I'm familar with this product, and here's the truth about it:

Swimming pool algae needs nitrates and phosphates to grow, reproduce, and spead, because this is the main source for pool algae.

Now, if you keep your pool chlorine level (the pool sanitizer) between 1.5ppm - 3.5ppm and cyanuric acid between 20ppm - 40ppm (the stabilizer for the chlorine), there won't be any algae or green pool water because the chlorine kills the algae.

If the pool chlorine kills the algae, what difference does it make what the phosphate level is? There's no algae to eat up the phosphates.

My YMCA pool has a pretty high phosphate level, I think it's over 1000, but it doesn't concern me because I keep the chlorine level up between 3.5ppm - 4.5ppm. This way there's enough chlorine to kill any organic matter and bacteria.

The yellow substance could be residue from the alkalinity up and soda ash. Normally yellow algae (sometimes called mustard algae) can be found in the shady parts of your pool and is swept away easily.

A good way of finding this out with your pool is to give it a good sweep, allow the dirt and debris to fall to the bottom, then vacuum the pool. You can either vacuum through the FILTER cycle or to WASTE. If you vacuum to FILTER be sure to backwash.

A day or two later come back and take a look at your pool. If you find yellow spots again and they can be easily swept away, you probably have yellow algae. If there's no yellow, then it might have been a reaction to the 3 chemicals you put in the pool, but to the best of my knowledge there's really no way of knowing, if you can't duplicate it.

If it is yellow or mustard algae you can go here to find the best way to kill it:

Yellow Algae..Mustard..Swimming Pool..Problems

With respect to pool clerks, I've found that the best place to get swimming pool care advice is from someone who has taken care of pools and knows the "ins-& outs" of pool water maintenance from real experience.

Keep you pump running a minimum of 10 - 12 hours per day in the Summer, or you could invest in a variable speed pool pump that can stay on 24/7 but uses less electricity because it's not going "all-out" all the time.

Best of luck with your pool and let me know how this turns out for you

Robert