blackish green pool

[dek]

We may be buying a home in foreclosure that appears to have been vacant for quite some time, and the pool is a reel mess. It looks blackish green, the green part is growing and looks like long seaweed. I think it is a gunite pool, but I am not certain (I'm afraid to feel the inside, and there is a structure over it so no one will fall in).

From what I have found in this forum it looks like maybe it can be cleaned up with bleach and a lot of brushing, but what about the plumbing, and pool walls? Is the plumbing full of this algea too? If it is would backwashing get rid of the algea in the plumbing? Would the neglect cause the pool to need resurfacing? (home was built in 1999 so I assume the pool was put in at that time). We have had pools before, but never one in this shape.

[muss08]

It's probably going to be necessary to drain the pool. Its the only way you can thoroughly check all aspects of the pool (plumbing, lights, surface,etc.). If you are in a cold climate the pool's plumbing lines should have been plugged during winterization and the water level should have been maintained below the tile line. If the chemistry was not checked while the pool was not in use and the pH has swung high or low then the surface could be damaged. If it is a gunite/plaster pool an acid wash should remove any staining. I've seen plaster surfaces last 20+ years if properly maintained.

[lonestar]

There is no way to know the condition of the plaster. It may immediately need a replaster job. All of the equipment might be dead. Check the prices to replaster and buy new equipment.

On the other end, the pool may be cleaned within a few days by proper sanitation and filtration alone. Ive cleaned pools that were brown where you couldnt see an inch into the water.

It is likely best to drain the water and refill, then take the fill water to a pool store for testing. Likely, youll be able to clean out the filter with a little instruction (take pictures of all your equipment to the store) and the rest of the algae will die after shocking and filtering.

NOTE: Draining a pool entirely may be bad news depending on your ground water/time of year etc. Ask professionals in your area.

[chem geek]

I don't disagree, but note that even pretty nasty looking pools can be cleaned up with chlorine alone as seen in this thread. This is just upon spring opening, however, and not a pool that may have been let go over an entire summer season (or longer). In any event, I would suggest physically removing as much solid material as you can first -- you'd have to do that no matter what. Then you can deal with the free-floating material (algae) either from chlorine or drain/refill as appropriate.

Green algae won't damage the pool surfaces (not much, anyway), but bad water chemistry can. If you test the water and it's highly corrosive (low saturation index from low pH, CH or TA), then the plaster may be pitted and partially dissolved.

Richard