Draining water out of a fiberglass pool with no sump pit before and during heavy rain

[ba67]

The remnants of Helene will make its way into our area bringing heavy rain and gusty winds starting tonight and lasting for the next 24-48 hours. Rainfall amounts through Saturday could reach 3-4 inches and the wind gusts could exceed 30-40 mph on Friday. In anticipation of this bad weather, my husband drained about 1.5 inches of water out of our pool because the water level was already a bit too high. He accidentally drained too much water off and now its about 1/2 inch lower than normal operating level. I read something online that says that you should never drain water out of a fiberglass pool before heavy rainfall so I wonder if we need to add 1/2 inch of water back so its at normal operating level. Do we need to add some water to the pool or will it likely be fine since its only 1/2" lower than normal and we are expecting an inch of rain tonight?

I'm also wondering if it will be safe to drain water out tomorrow if it stops raining for awhile so the skimmer will work more effectively. Winds could exceed 30-40 MPH tomorrow so we will need to lower the water in order for the skimmer to work more effectively. If we shouldn't lower the water out when more rain is expected, I think we will shut the pump off before the storms start tonight instead and keep the pump off for the next 24-48 hours since the skimmer won't catch any of the leaves that will fall if the water level is too high. Our fiberglass pool has no sump pit so we have no way to monitor or remove water that is under the pool.

 

[JoyfulNoise]

Do not remove water. You do not want the pool shell to float. I’d fill it back to normal and then let the rain fill it up. If it overfills then so be it … the last thing you want is for the shell to lift. A sump pit wouldn’t do you any good anyway … a dinky little submersible pump running full tilt has no chance against a deluge of ground water … that would be like you trying to empty a pool with a drinking straw … “spitting at the wind” basically.

Just let whatever happens happen. Your safety is much more important.

Are you able to protect the pool equipment from flooding if necessary? Do you know how to kill power to the equipment? Open drains? Where’s your flashlight and rain poncho? Figure those things out now so you don’t have to try to figure them out at 2am when the rain is pouring down.

 

[ba67]

Do not remove water. You do not want the pool shell to float. I’d fill it back to normal and then let the rain fill it up. If it overfills then so be it … the last thing you want is for the shell to lift. A sump pit wouldn’t do you any good anyway … a dinky little submersible pump running full tilt has no chance against a deluge of ground water … that would be like you trying to empty a pool with a drinking straw … “spitting at the wind” basically.

Just let whatever happens happen. Your safety is much more important.

Are you able to protect the pool equipment from flooding if necessary? Do you know how to kill power to the equipment? Open drains? Where’s your flashlight and rain poncho? Figure those things out now so you don’t have to try to figure them out at 2am when the rain is pouring down.

Its only 1/2" inch below normal operating level and it skims fine. Could it cause the pool to float just because the water level is 1/2" lower the normal?

If it isn't safe to lower the water level when it stops raining for a while tomorrow, I think I will get it up to SLAM level and turn the pump off before dark and keep it off during the duration of the storm since skimming action is poor when the water level is high.

 

[JoyfulNoise]

It’s likely it will be fine. Raising the FC preemptively is ok to do as long as you have sufficient chlorine on hand for afterwards. Remember, everyone’s pool is going to get trashed in some way so there’s going to be a run on liquid chlorine. Stock up if you can so you have enough on hand. Then let the pool ride out the storm and fix it later.

 

[sande005]

1/2" variation is very little, so as long as the skimmers skim, everything is fine. A lot of rain could potentially fill the pool up above the skimmer opening. In that case, the system will still circulate water and filter just fine. But anything floating on the surface will stay there (or sink when water logged) because the top of the skimmer opening is lower than the surface. There might be concern about water getting under the coping or decking if the level is so high it actually overflows the pool, but that depends on the construction. One usually has many inches between the normal water surface and the top edge, so only if you get that much rain will it be a worry. That would then call for lowering mid-storm.
Worst case (usually) - the water might be too high for the skimmer to skim and have to be pumped down after the rain leaves. And you'll have more stuff floating and on the bottom to net or otherwise clean out.