Green pool, please help

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Zeiglarre

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Feb 28, 2016
4
Greenville
Hi!

We are new pool owners (just bought a house with a pool). When we bought the house (end of Feb) the pool was a nice clear blue. We kept it that way for a few months, but it seems that lately it has been more green than not. My husband is good with chemistry and math and has been reading and following your forums and trying new things, but it still is green. Here is our set up:

We have a sand filter. We have a 20,000 gallon pool. We have an aquabot jr. pool cleaner.

Our numbers this morning are as follows:
FC 7.5
PH 7.6
TA 125
CH 225
Water temp 89* (at 10:30 am)
We are out of the CYA test chemical (on order supposed to be here yesterday GRRR!), but the test strip says it is 50.

The sand filter was registering 22 psi when we moved in and has been steady at 14 lately. We have added DE (about 1.5 cups) to the filter in the past few days. It is finally back up to 22.

What can we do to get the green out so we can enjoy our pool this summer?

Thanks!
 
Zeiglarre said:
The sand filter was registering 22 psi when we moved in and has been steady at 14 lately. We have added DE (about 1.5 cups) to the filter in the past few days. It is finally back up to 22.
Click to expand...


This confused me. Do you want the higher pressure, and if so, why? As the PSI of the pump rises, it's an indication of a less efficient filter and in need of a backwash. Adding DE to a sand is fine to get the finer particulates, but you should only add enough to increase the pressure by 1 PSI. Once the PSI increases by 25% over normal (i.e. fresh off a backwash), you need to backwash again.

What do you chlorinate with? Do you have any reason to believe CYA would be over 50 or even over your last CYA test? Pucks contain CYA, so as you chlorinate, you increase CYA with virtually no way of reducing it besides splash out, whereas chlorine is broken down by the sun, organics, and evaporation. Could be that if you chlorinate with pucks, it cannot get out in front of an algae bloom. Unfortunately, you won't know for sure until you receive your CYA reagent.
 
After intensive reading, we thought that the filter was not working as effectively as it should, so we added the DE in hopes that it would show that it was cleaning the particles. We backwash the filter as needed, but it is not very often. We have also been sweeping and vacuuming it. Even with doing that, the pressure never changed, so that led us to believe that it wasn't doing what it should. When adding the DE we only added enough to increase the psi by 1 as per the instructions. At 22, we thought it was finally working to clear out the green.
Mostly we chlorinate with bleach. We did use the Clorox xtra blue shock last week hoping it would help. It did raise the FC to 9 or 10, but the green never went away.
 
Filtering alone won't clear a green pool and as the pump pressure increases, it loses suction and return strength. Also algae tends to attach itself to the bottom and walls of the pool. So when you vacuum, you only serve to stir up what is not vacuumed and if the FC level is not high enough, the algae that lives will multiply.

If I were forced to guess based on the current info, I'd say you need to SLAM the water. However, without any confidence in the CYA level (strips are quite inaccurate), you can't know to what FC level you need to maintain.
 
Hello again!

So we were out of town for a week. Before leaving, we dumped in 5 gallons of the pool bleach from Wal-mart. A neighbor added a gallon daily while we were gone. The pool is much blue-er. The shallow end was very clear except for mounds of brownish dead algae at the bottom. We have been vacuuming and running the robot for several hours. The color is a little less blue, I'm sure because we have stirred up the algae.

The CYA reagent was waiting in our mailbox when we got home. Upon opening the package it, we discovered that the top had broken and the bottle was now empty! Grrr! We are now waiting again, for a new shipment.

Mr. Bruce - we are in Greenville, MS.
 
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