Grey water tank issue

[lanerboy]

I seem to have an issue with my grey water holding tank, I had a shower on the boat last night for the first time and the shower struggled to drain.

I have investigated it today and it drains really slowly and I think it is a vacuum problem with the holding tank because if I remove the lid off the tank it drains immediately. I then run the shower with the lid off and it works great but as soon as I put the lid on it fails to drain and bubbles out the shower floor.

AFter some research it seems these have a breather hose that exits out the boat hull, how do I distinguish which is the breather hose and does it look any different to any other pipe exits on the hull.

I'm thinking this pipe on the top corner may be the breather as there is no sticker next to it but I can't trace where it goes
Has anyone come across this issue.

 

[rafiki_]

I seem to have an issue with my grey water holding tank, I had a shower on the boat last night for the first time and the shower struggled to drain.

I have investigated it today and it drains really slowly and I think it is a vacuum problem with the holding tank because if I remove the lid off the tank it drains immediately. I then run the shower with the lid off and it works great but as soon as I put the lid on it fails to drain and bubbles out the shower floor.

AFter some research it seems these have a breather hose that exits out the boat hull, how do I distinguish which is the breather hose and does it look any different to any other pipe exits on the hull.

I'm thinking this pipe on the top corner may be the breather as there is no sticker next to it but I can't trace where it goes
Has anyone come across this issue.

Can you try and blow through the tube from the tank end?

 

[lanerboy]

Can you try and blow through the tube from the tank end?

No can't get near it, might have sorted it fingers crossed by forcing air down the pipe from the outside, it seems ok after testing but will see over the next few days

 

[Boathook]

Is the breather outlet blocked on the outlet of tank ? with the lid off are you able to feel the hole ?
Can you get the hose off and rod it or extend the hose ? and somehow put a vacuum on it to suck out any muck, just in case there is a filter on the end.