This is much more than DIY.  Impressive, but beyond my level and time.  You are likely to be in construction.

Just curious, why don't you guys using liner instead?  I have been using liner for small ponds, so far so good.  Can be done in a day.  And I am about to do a bigger one later.

I just use the canvas for lori, the green one.  Granted, it is only being used for less than 6 months, and w/o much direct sun light.  Not sure how long lasting it will get.

But if you look at youtube, the kuailo all use liner rather than using concrete.

ps: I also do a lot of DIY myself, mostly I hire indons to help.  They do the heavy work, i give them instructions.  Hurt my back, so better let them do the heavy work.  :-)

Also, why not use aquaponic as filter?  it is almost maintenance free.  If don't wanna grow vege, and replace it with plants.

My DIY fiber pond..took me 2 days to finish up as picture attached including digging 7 inch down the ground....total cost around RM350 only...Everything bought from Sg. Buloh...FYI the tank size is only 2 1/2 ft x 3 ft....