Whale Gulper Grouper and non return valves.

[5teve]

Hi All

Long time lurker finally a poster...

I installed a black water tank 5 years ago, it originally had a macerator pump just above the top of the tank (all top entry/exit tank) after 3 years it finally rotted out and I replaced it with a whale gulper grouper mk3 as it fitted my space requirements. I know its not a black tank pump, however as its fundamentally the same as the other gulper pumps I went with it.

The instructions says primes to 1m but then says it should be mounted below the level of the tank.. I didnt its level with the tank top.

So its been in for a year or so and had gradually been getting worse at priming and pumping out. It works fine at speed underway as the outlet obviously gets flooded, shuts the triscupid valves properly and it can prime correctly. So a few questions..

1, is there an inline alternative to the triscupid valves? ie a non return valve that connects the pipework?

2, How often do you replace your triscupid valves

3, Do you have all your black water pipework disconnectable? I have to heat the pipes to remove and its a pig of a job.. i was thinking about adding PVC pipework from tank to pump with disconnects in (still have to use some hose though) - Thoughts?

Thanks in advance

Steve