using citric acid to remove metal stains...

[river-wear]

Hi everyone,

I read several threads on here about removing stains and really appreciate the knowledge stored here! I brought my Chlorine level down low (0.5-1ppm) last weekend, added polyquat and about five pounds of citric acid on Saturday - roughly following mbar's sticky. It's taken a couple of days but most of the stains are finally gone. There are a few stubborn old ones still on seat area but nearly all of the ones on the walls have disappeared.

Following PoolDoc's advice to someone else on another thread, I've begun adding Chlorine while keeping the pH at about 6.8. So far the Cl reading keeps going back to zero, even with the saltwater generator running. My main question is whether I should add a trichlor puck to the skimmer? (Another bit I picked up in another thread that I understood to mean it can help precipitate out the metal to catch in the filter.)

I should have mentioned that I've also put in "PoolTime" brand Metal, Stain & Scale out per the instructions on the bottle - which means 2.5 32oz bottles. The idea of course is to keep the metals in solution as the Cl goes up. My CYA is about 40 last I checked. The pH falls whenever I add water to the pool, so I usually have to add 1/2 gallon of muriatic acid at the same time. Also, if it matters I do have a pool heater but we've never used it. It's been four years since we had the pool refurbished (fiberglass coating over concrete) and metal stains haven't been a big problem. They started to appear as little speckles on the sides last year but I didn't do anything about it until now.