One day he forced in the wrong end of the hose down the line by mistake. Once the house got
past the 45 degree angle's the fitting at the end of the house got stuck, and would not budge.

Well, we were in big trouble, with a stuck hose that wouldn't budge...

After several house of trying to get the house out, a light bulb went on in his head. He tied a rag (boy scout knot) in the center of a very long strong nylon line. He dropped the line down from inside the first filter tub
all the way through, once it got all the way through, he tied the one end of the line to the dock.
Then he began pulling the rag through the line from inside the tub, then he tied the end of the line
to a crate just outside the first tub. Then pulled the line attached to the dock, again pulling the rag through all the way.
He alternated pulling both ends of the nylon line until the vacuum hose loosened and he was able to be pulled out the stuck
hose

The nylon line in now part of his regular maintenance...It is now so easy to keep
the drain line free from any debris.

The long nylon line (with the rag in the center) is now permanently attached in our pond --- the nylon line is attached on one end to the dock and on the other
end to a crate (just outside the filter tub)
He pulls on it to loosen and remove leaves, pebbles, etc...as part of his normal maintenance. There is no longer a need
to drag out the shop vac and vacuum out the drain line,
when it gets clogged... Also, the clean drain line helps keep the pond running more effectively,
thus, there is less filter maintenance as the clogged lines always slow down the flow of water in the filter tubs.
He cleans the tubs a lot less since discovering this trick.

BTW...he initially used a snake to get the line all the way through the drain line...

Here's a drawing of the pond set up.

The nylon cord is attached to the dock cleat.

I had to go swimming yesterday to unclog drains. I knew they were starting to run slow and needed cleaning, but of course while I was away for the weekend my poor DH had to try to keep the filters going with the suddenly even more reduced flow. I wish I had thought to run a string through the actual drain lines and clean them while I was already wet. I am sure the drain lines have a lot of icky stuff on the walls after 5 years in service.

I installed a retro BD this spring on my existing pond, through the side, but if I ever do another rebuild I will be installing a through-the-bottom BD, so I'll be tucking this away for future reference.

One more thing, Cliff took the dome off the BD and just has a black milk crate over the BD. This way he can tug on his nylon cords frequently without having to uncover the BD. It's all about -- making the maintenance easier.

Check out these stones surrounding the BD (under the milk crate) Where do they come from? (This is suppose to be a bare bottom pond) I swear these koi pick up rocks in their mouths, roll them around and spit them out around the BD to clog it up!
Well, we're smarter then our fish, cause we outsmarted them :)
anything that gets past the milk crate, get's taken care of with the " rag on the rope"...ha!

That's a great trick.

>>>Check out these stones surrounding the BD (under the milk crate) Where do they come from? (This is suppose to be a bare bottom pond)<<< Yeah,LOL .... I haven't figured that one out either!

Hey, Ma's not looking, lets start digging the rocks
outa that lily pot over there...

The water and Koi look lovely as always. Just a pleasure to see your pics.