Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
"what size drill bit and bulkhead should I use for a tank that size?"
I am running 1" PVC on my 125 gallon tank and it is barely enough, but I am not running a bean animal system. 1" PVC might be plenty for that (better) system. So go get the bulkheads and see what size drill bit they call for.
"Is plexi ok to use for making overflow walls?"
Plexi is hard to unite to glass. I would really seriously try to use glass. Silicon works great connecting glass to glass. Also, 125 gallon (6' long) is a long run, you might want some mid-tank bracing in the overflow.
"Also how much space do I need in overflow to fit herbie?"
Depends on the pipe size. Figure that out, then go buy stuff like the elbows and bulkheads. Do a dry run, perhaps using a cardboard box as a tank, and test fit some more cardboard as an overflow.
"And for a tank my size do I need two overflows?"
If you decide to use 2, then I would duplicate the whole set up: 3 pipes in each set up.
"Meaning a herbie main, and emergency IN Each?"
"Also I've read that bioballs as filtration in sump may use up nutrients that the plants need is this true?"
Nitrifying bacteria will grow on any surface (bio balls, sponges, floss, poret mats, lava rock and more). They have a great capacity for removing ammonia, but they turn it into nitrate. Plants can use ammonia, nitrite and nitrate as sources of nitrogen.
So, yes, bioballs (and anything else that houses nitrifying bacteria) will "remove" or "Use up" ammonia, one form of nitrogen that plants use.
But which would you rather have in the tank:
Ammonia? Nitrite? (dead fish)
Nitrate? (and live fish).
I think the horrible comments about filters being 'nitrate factories' are missing the point. If all that ammonia was NOT getting turned into nitrate what kind of tank would that be?
"Any suggestions how I should have my sump set up?"
Only that if you can cover it (seal it) you will conserve injected CO2.
"I'm planning on using miracle grow topped with kittylitter..."
Skip the kitty litter. Use Safe T Sorb, Turface or similar. The color is nicer (unless you like white to off white)
"...mounds in the corners... anaerobic trap or something and killed everything...anybody have problems making mounds with miracle gro?"
Thriving plants will ADD oxygen to the substrate via their roots. This will minimize anaerobic pockets, so keep the plants growing well.