Bell,

Are you going with plexiglass or glass for the viewing panes?

most likely glass, i'd like plexi as i can get it cheap but silycone doesn't adhere to it well.

The silicone adherence shouldnt be much of an issue, as the water pressure will foce the plexi against the silicone, thus basically turning it into a gasket of sorts.

Glass is however probably better, since it is less scratch prone. You guys are then also lucky enough to have acces to low iron glass in the 'states, which has far better optical characteristics than the normal "green" stuff!

there have been many people who diy their own tanks and tried the silycone with plexi.....it'll hold for a few weeks but they all developed leaks. i'm currently looking into an epoxy or something of the like which is potable (won't kill fish), then build channels for the plexi to slide down into with the epoxy surrounding it.......i'm a ways off from deciding which to use.

once the basic tank is built it will get filled to test for leaks. once drained i will cut the front panels for the windows, build the background/floor. then install/seal the glass. after it's done it needs to cycle until the chemicals from the concrete has leeched out. when the pH is stable the fish go in :D

i will be getting my tranny back for my 911 this weekend (had it rebuilt)......so that's the next task before i start on the top part of the tank.

Man, I'm jealous! Though admittedly this gives me the chance to learn from your experience before I tackle my own tank!

Go glass. Heard of too many people with scratched tanks. One guy had a snail scratch his tank up bad.

Wow, that is cool. I thought I was doing well with a foot and a half long Jaguar Cichlid in my 135 gallon setup. He is in there alone, tried to eat his roomates, had some success in this before he went into solitary.

Exactly my thought. Most residential basement slabs are only 4" and most don't even have reinforcing except for WWF (welded wire fabric - the mesh stuff). It's strong, but not strong enough for a super-heavy point load like that. For what you're considering, I'd actually trench out the slab and pour in a thickened portion to carry the weight. If you're carrying it to columns or posts ultimately, I'd absolutely add some footings (even small ones would do) underneath. You could alternatively build up a pad for the tank - kind of like the equipment pads they use under heavy equipment like generators or fuel tanks. That'd probably be okay too.

Water is wickedly heavy - heavier than you think. Over a long period of time it could absolutely cause deformation and cracking to your slab.

Should be an awesome tank though.

Wow... keep on posting... you should create a separate website/blog to document this...

the new tank hasn't gotten too far along......still developing some things, educating myself on some other things, but all in all the ball is slowly rolling.

i just got done building a stand for my 2 75 gallon tanks, both will sit side by side and run off of one sump system, this sump is the "prototype" for the river tank, should have the first 75 gallon cycling by the weekend.

i will be building one test tank which will be 240 gallons so i can get accustomed to the epoxy i need to use, should have that done in a month or two. the test tank will end up being used and will be flushed in the wall behind my bar.
once that holds water i'll have the confidence to start cutting $400 in plywood for the river tank:D

and the floor will be fine....the river tank will end up being approx 650 gallons which is about 5200lbs in water....add another 600 for the tank/decorations, so less than 3 tons....my basement slab is plenty thick enough.....almost 8", so no worries.

i was over a fellow fish guy's house this week so check out his diy 1200 gallon plywood tank, it's foot measures 14ftx3ft....very impressive stuff.

Join those two 75s with a tube "bridge"

http://www.bio-elite.com/waterbridge.htm

... I'd just eat the fish. ;)

A quick search on www.concrete.com forum:

What strength concrete is normally used for the slab under a home?
Typical mixes range from 2500 psi to 4000 psi, depending on the area of the country and the quality of the raw materials. Should there be a different weight used for the garage area? Not really. Usually the biggest load on a slab is the heaving from the subgrade and not the structure on top of it (or the car.)

I would not drill or cut into the floor because that could let water in and that is more trouble than worrying about a 2500 psi compresion strength of your floor.
800gal h2o= 6672 lbs
bldg materials=1000lbs
total wt= 7672lbs

if you support the tank on 8 two by fours then: 1.5*3.5*8=42sq inches

7672lbs/ 42 sq inches= 183 lbs per sq inch

You should not worry.

Wow, thats going to be nice. I use to breed and raise African Cichlids for many years and looking to get back into the hobby. There are alot more variations available now then there was when I was in the hobby in the late 70's and 80's. Can't wait to see your tank finished. I want to build another soon also.

kycarguy.....check out http://www.cichlid-forum.com/phpBB/ they have a great diy forum (my tank is in there somewhere), there's a handfull of people who hide behind their keyboards......but that applies to all things internet :D

made some progress on the 75 gallons......
here is a background i made out of about 160 lbs of concrete, the overflow for the filtration will be hidden on the top left, it'll also split into 2 pieces so i can get it in the tank.
the second 75 gallon will have a matching background.

http://forums.pelicanparts.com/uploa...1158001499.jpg