First drilled tank
- Thread starter soco
- Start date
You have a lot of latitude here. It actually doesn't make too much difference. It's much more dependent on the exact type of overflow your using and where you need to route it to your sump.
Usually manufactured tanks place overflows in the corners or off center a bit in the middle of the tank.
You can't go too far wrong here.
Usually manufactured tanks place overflows in the corners or off center a bit in the middle of the tank.
You can't go too far wrong here.
Squatch XXL
Well-Known Member
^ This is 100% accurate. Before you make ANY planning on where holes are, pre-fab your plumbing, and make sure it has any and all adjustments you will need. Once you are committed to a certain vertical height, you may not be able to make changes. I cannot "upsize" my durso 3/4" overflow because I simply do not have the head room. this was a tradeoff during the decision phase. Either I have the overflows to the bottom of the tank, or I settle for a bit more discreet with non-typical designed plumbing.
I drilled my 40 (see my chronicle), and was limited by a few different dimensions and "Personal feelings".
I will be re-doing the whole process again here shortly on an 85-90 gallon tank that I just picked up.
The size of the hole needed directly correlates to the size of the bulkhead that connects through the glass hole. BRS sells a whole assortment of metric hole saws that are specific in size to standard bulkhead fittings.....Keep in mind that the hole will be quite a good deal larger than the actual plumbing (I.e. a 3/4" bulkhead requires IIRC a 1-3/8" hole...or the metric equivalent.)
ALWAYS stay at least one drill bit width away from any sides of the glass or any other holes. Basically if you have to have a 2" hole, you should be at least 2" inches away from another hole.
If you are drilling yourself, save yourself the headache and make a jig out of a piece of scrap lumber. I have not used a jig yet, but I will be making one for the upcoming project. It is very very tricky to start a hole by hand drilling. If you have no experience in drilling large holes with diamond carbide bits, I STRONGLY recommend a jig.
Drill as few holes as necessary. I am aware that all the MFRs sell reef ready tanks with holes pre-drilled. This is not a great example, because most RR tanks have tempered bottoms....basically the holes are drilled, then the glass is tempered to increase its strength.
Drill slow, and at low speeds. Flush out your water dam as often as possible to keep where you are "cutting" through clean. I use the term "cutting" very loosely. It is not cutting as much as it is slowly grinding the glass away from the bit.
Most important. Stay calm. If you feel at all uneasy about drilling glass, don't do it. I know how much of a bad name that HOB overflows get but they are still cheaper than the cost of a glass drill bit, a broken tank and a trip to the ER with multiple lacerations.
SubRosa
Well-Known Member
Hell yeah! Light pressure and slow speeds are always important, but on smaller tanks where the glass is normally thinner it's critical. Another trick is to place a patch of tape on the underside of the area being drilled. It can help prevent the bottom face from blowing out and leaving an uneven surface which could potentially cause problems with bulkheads sealing. I've been paid to drill lots of tanks, and the guy who first taught me how and paid me to do it said to remember that I was getting paid by the hour, so milk it. That sums up the philosophy of drilling glass as well as anything!
desertcelt
New Member
I agree with DaveK. My first drilling of my BioCube included one return hole, but I should have just gone over the edge. Although it didn't leak, it was a weak point and I would never drill for returns if I had the opportunity to do another one.