Drilling Glass Tanks

[darkdep]

(Thought I'd stop thread jacking tuvok's post)

I'm still not certain what sort of filtration I'm doing for my fishwall, but I keep coming back to systems that require holes in the tanks.  I've read about it and being handy, feel I could do it myself.  So, here's a few Q's for the experts...

- Let's assume for the moment I'm doing a sump setup.  Do I need TWO holes per tank?  Or can I return over the top?  Any technical or esthetic reasons to go one way or another?

- Diamond bits seem to be the tool.  If I do this myself, I'm thinking of using a piece of plywood behind the glass being drilled to provide support and minimize cracking and blowout at the end.  How large a hole should I be looking to drill?  These are 75gal and 40gal tanks.

- Bulkhead fittings...where do you buy em?  Do they glue and screw in place?  Do they have to be a perfect match to the hole?  Or do you have a little play incase the hole doesn't come out perfect?

- I'd like to be able to disconnect any hoses from the tank for cleaning.  How do people practically do this?  Allow to drain then disconnect, or put in a ball valve directly after the bulkhead and disconnect from there, etc?

Anyone have any pics of actual drilled setups on their tanks with info on procedure or parts?

Lastly, I know there are places that drill glass for a fee (I keep hearing $25 / hole).  Anyone know if you can get a discount with a lot of holes?  I'd be looking to get 12 holes minimum...

Thanks folks.

[Chinaman]

Hello Chris, again:

Thanks for putting together the group order for the heaters..and
thanks Bubblefish for parting one with me.

First off, I am no expert on drilling glass tanks, but during my
research life eons ago, I did use a "flow-through" setup to
do bioassays...

Not sure it's still practiced in this century, but we had a set of tanks
holding yearling rainbow trout and the American flagfish. There was one hole
per tank, at the bottom.  The size of the hole will depends on the
dia of the standpipe (or overflow pipe ) you want, which in turn depends on the
overall turn over rate you want.  The standpipe then
is inserted into a rubber stopper (with center drilled). Rubber stoppers are
available at any scientific lab suppliers. And the rubber stopper is
then inserted into the hole. This pretty much will address your
concern regarding the size of the hole. In my opinion, one hole is better than
two, either for cosmetic or "flood control" reasons.  I remember seeing
a similar set up at a Los Angeles pet store as well. Not sure if this would help.

Sam

[bitterman]

I'm definately no expert on drilling glass, but I have done it a couple of times.

1) use a drill press whenever possible
2) Use a diamond hole saw
3) Use plasticeen to create a dam around the area you will be cutting in
4) Use whole milk as a lubercant and for cooling (It work suprisingly well, and maked the drill bit last much longer)
5) Use next to no preasure. Daimonds basically grind though the glass and this must be done slowing otherwise you could crash the piece of glass you are drilling.
6) Clamp the piece of glass in place so it can't move (Be carefull to much preasure and you will break the glass)

Hope this helps,
   Bruce

[babblefish1960]

DO NOT DRILL THE TANK BOTTOMS, unless you know for certain they are not tempered glass.

Having a wooden support against the glass is a must, and only one hole is required. Bulkhead fittings aren't too expensive, and they come with gaskets and give lots of leeway insofar as coverage is concerned. In the final analysis, you will find it is cheaper and far less stressful to farm out the drilling, as busting glass is a real downer. I'm sure you could get a package deal if you phone around, but no one guarentees holes won't have failures down the road.

There are a few good private systems locally, and a few coffee chats and inspections could prove to be time well spent, as you don't want to build something that doesn't work how you want it to, and feel forced to change everything later. Your lally column is in the way of this, and having someone come around to help you design would be good planning to forestall frustration and grief.

All the negative disclaimers having been said, for what you're doing, it is good money sense and keeps the system manageable so you're not spending all your free time working at simple maintenance that can be handled more easily with a central system.

Talk to the guys at Marinescape, they are knowledgable in this arena, and can offer ideas and contacts, and even better advice. Good luck with this APW

[darkdep]

I won't be drilling the bottoms; I know about tempered glass and won't have to deal with that.  Idea at the moment is to connect 2 75's together, and 2 sets of 3 40's.  The drainpipes will drop down to some sort of bucket/sump style filter, with a pump per tank to return water.  This will give me a minimal number of filters to clean, and still give me some flexibility WRT water chemistry and disease control.  I will keep the 10's on air-driven box filters. 

I don't know how to figure out how big a pipe I need.  For the stack of 3 40's, I'll want to do about 6x per hour, so about 240gall throughput per hour per tank. 

I'd like the water flow to not come solely from the top; as I will be keeping Africans and want to suck up the poop.  Is it possible to, in the aquarium side of the glass, have a "T" that goes up and down...the down goes near the tank bottom with strainer to pull from there, and the top goes to where you want the water level to be...Assuming that if the water level drops too much the siphon will be broken and the tank will no longer drain in the case of power failure.

[babblefish1960]

Bernoulli is a name you should look into, he will help you with calculations regarding laminar flow and turbulent flow. Factors involved that are very important, are gph at x head height, and length of piping involved. You will also need to resolve the number of elbows in your set up and how exactly you wish to divide the piping to distribute similar rates to two stacks of tanks at differing heights.

Not impossible by any means, but a lot of math calculating involving many variables. the type of pipe you use will determine the pipe roughness and how this affects the turbulance. I also remember requiring fluid viscosity and friction coefficients both with the piping, and the pump.

I don't mean to make it sound scary, but you only want to put this together once rather than experiment with all the variables with continual modifications and strip downs.(who has that sort of patience, money and time?). As I said earlier, you have a lally column to get around, which increases friction, and complicates the piping, but with some help in the math, can be overcome.

Your desire to turn over six times per hour will actually put your requirement for a pump around the 1000gph pump, as you're rising a head at three locations of about six feet or more, and as each tank will need a regulator of some sort to control individual flow, as well as needing to be by-passed on demand, you'll find the math will likely point to about 1 1/4" pipe for distribution, and 1 1/2" for return. This is off the top of my head, so it ain't gospel, just a hitchhiker's guide. The distance from the sump to all of the tanks is also a factor, your setup is compact, so it isn't too bad, but the size of the sump is important so as to be able to hold all the excess water when there is a power outage.

You may want to install two pumps that can be put in service in parallel yet individually take over should one pump fail. Redundancy is a watchword when you have so many lives depending on just one system.

The plan for using a t-connector to siphon water is a good one, simply put the top portion high enough to account for too much water, but have the tee located at a height suitable to break siphon without flooding the basement or emptying the tank. Simple and effective. Your ideas are reasonable and sound, they just need some paper tuning with a calculator and some good formulae.

Good luck with that and let us know how it is going with the figuring.

[BigDaddy]

I don't know how to figure out how big a pipe I need.  For the stack of 3 40's, I'll want to do about 6x per hour, so about 240gall throughput per hour per tank. 

Well... All-Glass Mega Overflows use a 1 inch drain pipe and they are rated at 600GPH...