Backyard Aquaponics
A place to discuss aquaponics

The company here markets them for use in capturing grey water - though those models have 4 wheels rather than 2, so perhaps they are built stronger throughout.

Will have a talk with them... Was thinking of sitting it into some wet concrete so the base is fully supported - on some I've seen the rim if lower than the center of the base causing flex.

What that numerical analysis did show me was that tall and thin was not best - makes sense when you think the filter works by slowing the velocity of the water as it moves radially outwards. Lucky as I did contemplate making one out of 150mm pipe at one stage!

Couple of things.

I am sure someone a few years ago used wheelie bins in Perth as FT,s, and they still have a weight rating on them, but this is more for the auto pick up than what the carry static.

I have a suspicion that the collision rate is responsible for clumping and that the height of the central chamber carries a relationship to the diameter and height of the vessel used, I also suspect that the stilling well could be replaced in that situation by a physical barrier to water moving out of the filter at speed. There again I have never tested this so its only speculation (and I have had a few beers).

There have been a few members use wheelie bins as fish tanks in the past hehehe

viewtopic.php?f=1&t=1064&hilit=wheel%2A

Hmm... where were you on the discussion in the mantis thread about filtering, where the exact opposite effect was given about collisions were a factor in causing more suspended particles rather than clumping?

I would imagine the velocity of said collisions would have a bit to do with it. High velocity would create smaller particles, slower larger. That is why there is an optimum flow speed in the filters.

Try page 8

I think my eyes glossed over by then...

I'm about to knock up several RFFs and want to put a cone shape into the bottom to aid getting the solids out easily for my wicking beds. Any advice on which waterproof sealing paint to use (or any other clever ideas to make a cone?).

I'm thinking of doing the cement mixed with perlite followed by a fine render and then sealed with paint. Other options are to seal with a pond liner and sikaflex OR try and plastic weld (or sikaflex) a cone into the blue drum (don't fancy my chances on that one!!)

I saw one on youtube somwhere, they used cement render down the bottom and a piece of plastic cut to shape and then pop riveted.

Are you talking Urbanfarmingguys Jay?

Matt, i recently used concrete on mine, sorry yet to tell how well it works.
I didnt bother with perlite ( i forgot to add it ), weight isnt too bad, it only took 2 bags of sand/cement mix.
It was hard to get inside to make the cone shape. I didnt have the patience to make a proper cone, so i simply used sikaflex pro as a coating over the cement.

It was kind of hard to spread, but once i realised i can just scrape it on as hard as i could and it stuck well, then it was gold.
Ended up pretty nice, but its not 100% sealed and am not 110% sure the sikaflex wont peel off one day.

I guess perlite is pretty exxy compared with sand- maybe I'll use a bit of old ag tube round the outside and concrete over that. I've got the cone calculator from http://www.gardenendeavors.com/rack/conepage.html
so might try and knock up a cone.

Wonder if Al. rivets are ok? Think they might corrode in acidic slightly salty fish water. Maybe SS is a better bet, though they tend to compress very heavily and may squash the plastic?

You should be able to get longer shaft rivets, maybe do a test first?
with the small amount of al. that you would be using, i wouldnt worry to much about it, it doesnt corrode that quickly i dont think.

Use a stainless steel fender washer to distribute the load. Find 316 stainless if you can. It is more corrosion resistant than the 18-8 or 18-6 most stainless fasteners are made of.

Thanks Ron - Yeah got heaps of 316 washers about for fitting gear to my fishing kayaks.

Sorry if I am resurrected a pretty dead topic, but reading through this was really helpful.

For my next build I have materials for a 1000lt FT, 2x250lt GB's, and then a sump/raft at the bottom end.

I was thinking it might be worth putting in a RFF in the system so the sump/raft is pretty clean water. My plan was to put this in after the GB, and before the sump/raft. Is this this best plan? Or should I put it in before the GB's.

Appreciate your advice.