- Jan 4, 2016
- 5,392
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
The hydrostatic valves I've seen here are kept closed by a stainless steel spring and they open if pressure outside the pool exceeds pressure inside the pool. Your property and the pool would have to be lower than the surrounding land for ground water pressure to exceed the pressure from the water in the pool. You would probably notice some dirt or dirt colour in the water down in the main drain if this was happening. Sometimes they get stuck open during the build from grit or no o-ring and that type of thing, but not real likely. That type needs to be replaced every 6 or 7 years.
That did get me wondering about the extra pipe riser in your equipment picture, which I believe is attached to your main drain (the one in the pool, not the one in the cover pit), but hasn't been used for anything. Is there any sign of water seeping out of that? Is the cap on that pipe glued or just stuck on it to keep it clean? Sorry, grasping at straws a bit, but we need to figure out where the calcium went! There's only a few things that can cause the CH reading to drop - water removal and replacement with lower CH water (e.g. backwash, overflow, drain-refill, or a leak), and testing error.
TA will drop from acid additions. CYA does drop slowly always, but much more from water replacement.
That did get me wondering about the extra pipe riser in your equipment picture, which I believe is attached to your main drain (the one in the pool, not the one in the cover pit), but hasn't been used for anything. Is there any sign of water seeping out of that? Is the cap on that pipe glued or just stuck on it to keep it clean? Sorry, grasping at straws a bit, but we need to figure out where the calcium went! There's only a few things that can cause the CH reading to drop - water removal and replacement with lower CH water (e.g. backwash, overflow, drain-refill, or a leak), and testing error.
TA will drop from acid additions. CYA does drop slowly always, but much more from water replacement.