Gravel coming out of the water pump, is there a cement counterweight?

difficult to do much there. you could try gluing something to the bowl, but it is very unlikely to hold for many cycles. you can buy new outer bowl / frames from the manufacturer.

no, not enough actual cement for the mix look into getting more.

The problem was you didn't fill the tank with water or added the gravel to fast and now the lateral assembly is broken and letting sand into the pool. You'll need to empty the tank and replace the laterals. Add gravel slowly after you fill the tank half-way with water first.

John

Hello. The typical volume-ratio for a self-mix concrete in this application would be one part Portland cement to three parts sand. For a stronger pad (capable of higher stress loads) it would be as low as two parts sand, but this is not necessary for a standard patio pour. The gravel should be three parts, more will make it tougher to achieve a smooth finish. Re-cap: Portland cement - 1 part, sand - 2 or 3 parts, gravel - 3 parts. Hope this helped.

There should be mixing instructions on the bag of concrete, but it is 1 part cement, 2 parts sand and 3 parts gravel.

cement counterweight inside case might have come loose or fell out

but that cement block does not go inside of the drain pump.