sump plumbing troubles

Ok im having troubles with my plumbing. my tank is a 75g my LFS drilled my tank for me. I put the skimmerbox on my self and did all the plumbing my silf. Its all 3/4 pvp. The trouble is when the power gos out or i clean the tank the timeing is off for the water to go back into the tank from the sump. 1 its to fast or 2 its to slow from the drain so i get the toilet flush sound so then i have to play with the ball valve at the drain to get the right flow back. I T of my drain one to the refum and 1 to the center of my sump. I like a slow flow in to my refum.
my pump is a quiet one 3000/780gpr

 

Do you have a picture of the inside of your overflow box?
If you have room you could add a T with one end capped and drilled, add a piece of air hose in the drilled cap and use a air regulator valve to tune it. The other side of the T stays below the water line inside the box. This will help control the amount of air that enters the drain and stop the flushing.

 

Very dangerous to have a shut off valve on the OF leg to regulate flow. You should regulate water put in the tank, not taken out. If ANYTHING gets in there and starts to restrict flow back to the sump..one of two things is going to happen:

1. You are going to add more water then the OF can return back to the sump and it will go all over the floor.

2. You will put so much water in the display that the return pump chamber will run low on water and burn the pump up.

 

1 and 2 is what im gitting alot of :/ otty i think i may just need to put a bigger pump on one that can do like 1000gpr. I will get you that pick as soon as i can silver its bed time right now

 

#1 ditch the glass lid it'll cause you major issues down the road

#2 this coule be several things, what Otty said is exactly right but to me it looks like the check valve might be on backwards which would cause issues with serious flow restriction also the toilet flushing sound could be air in the pipes, you need to have some way on the overflow pipe to get air into it, this helps to exhaust it and also muffles it

 

Here is that pick silver. I think i have room in there

 

To eliminate the flushing sound. You will need to create a Derso pipe (Google Derso)
To do this to your current set up you will need to start at the bulkhead. Right from the bulkhead put in a PVC 'T' then resume the PVC down to your sump. On the upper part of the 'T' you place a PVC end cap. Drill a hole in the end cap to allow air in. Drill a bigger and bigger hole until the flushing stops.

 

+1 on what Jason said, I did this and when I was done it was so peaceful, But I modified mine a little bit. I put a strainer cap on mine and stuffed a piece of sponge in it to quiet it down a bit, found it gave me a better flow to my sump.

What ever you do you have to bring the cap above the level of the water in the tank or it will come out the hole.

 

I need to add this to when my ball valve on the UF is at full open. this is when i get the flushing sound. I think the water is moving to fast to the sump for the pump to push it back to the tank. not sure just new to a sump

 

That is not possible. It is the pump that is "Over flowing" you tank to force water back to the sump. The absolute MAX flow from the tank to the sump is the Max Flow of the pump. You need to introduce air to the drain system of the overflow. the sucking sound is the siphon break as the pipe gasps for air