Gunite pool heavily pitted over winter

[noworries]

Just bought a house barely a year ago. The pool had been re-plastered maybe 8 years ago. It was in ok shape.

When it got too cold to swim I covered it and let it go. It turned into a swamp. I shocked it with bleach and cleaned the filter and it's crystal clear blue now and 75. I jumped in today and the plaster is incredibly rough and heavily pitted.

So my question is--what did I do wrong, and what should I do to fix it? Is there a DIY fix for the surface, or am I stuck hiring a contractor? I'm very handy--and I can't afford to drop $5k-$10k having it replastered!

Specs: Pool is In Ground, approx 28k gallons, SWG, in Socal.

[JohnT]

What's your pH and Calcium levels?

[noworries]

They are good now, the PH was probably high during the 4 months or so though. I've got some DE leaking into the pool because I have 4 filter elements that have damaged connectors... It doesn't feel like it's DE that's causing the problem though. Would the PH being high for a few months do that?

[Poconos]

If your calcium level (Calcium Hardness measurement) dropped too low, calcium will be removed from the plaster surface probably causing your problem.
Al

[mas985]

Or if your PH, Alk, calcium got too high, your might have scaling. Sometimes that can seem like pitting.

To fix it, there are a few choices that I know about:

1) Replace plaster. $$$$
2) Drain and acid wash. Unless you are daring, it requres a professional.
3) Lower PH and alkalinity and brush brush brush. This much like an acid start of a new pool. The idea is similar to 2 but does not require a drain but does require a lot of acid and baking soda. You drop the alkalinity to zero for a few days and brush the pool three to four times a day. Then you add the baking soda to rebalance the pool. Note that this method like #2 will reduce the surface life somewhat but it is much less expensive than #1 or even #2.