700 gph overflow kit

Use a smartphone to find out if you have tempered glass. This is cool

http://youtu.be/Yb9K3IGXwC0

 

Also the RC calculator royally sucks IMO. The reason I say this is because it doesn't take into account the surface tension effect of running water through teeth, and doesn't offer a figure or allow input on how much water height you want on the teeth or over a weir (a non-teeth overflow wall). the "Linear inches of overflow" they give you is ambiguous at best. What it really means is the linear inches of water actually flowing through to the other side, which is the sum of the width of all the notches, but they don't tell you that explicitly, or at least, it's not intuitively obvious.

Instead, I went to a fluid dynamics book and talked to a few reputable tank manufacturers.

If you are running an overflow with teeth, then the equation is this:

Q = 288 * C * L * (H ^ 1.5)

Where:

Q = flow in GPH
C = discharge coefficient
L = total length of weir (or additive length of notches)
H = height of water above the weir (or lowest point of the notch) and note that this number is to the power of 3/2 or 1.5, or the square root of H cubed. This results in a non-linear relationship between flow rate and water height, which is what the RC calculator is missing.

With a weir (no teeth) C=1.0. With 1/4" slotted teeth, C=0.55

If you take a 700 GPH glass holes kit, which has (12) 1" tall teeth each 1/4" wide, then L = 12 * 0.25 = 3". C=0.55. H=1.0 Q = 288 * 0.55 * 3 * 1 = 475.2 GPH. if H = 1.25", then Q goes up to 664 GPH. Q = 700 GPH at H = 1.29". So the glass-holes overflow maxes out at 700 GPH, after that, the additional flow is over the top of the box, which is then treated like a weir with a length of about 12 inches and you can get a ton of flow with 1/8" of water over a 12" weir, like another 150 GPH, and 430 GPH with 1/4" over the top. This of course can get you into trouble if you install the overflow box such that the top of it is right at the tank trim on the inside and you try to push more than 700 GPH through it.

Also the flow through a pipe is not as simple as the RC calculator suggests. If you run a full siphon overflow through a 1" pipe, the flow rate possible is dependent on the vertical drop, and can be several thousand GPH. Run a durso for the same distance and it's a fraction of that.

Anyways, the best thing to do w/r to your pump flow is to actually measure the flow and not rely on head loss calculators. To do this you would use a 2 or 4 qt pitcher and measure how long it takes to fill it. Repeat the timing step about 10 times and average then out and then convert to GPH. If your tank isn't set up, then put the pump in a sink and attach a return hose to it of the same diameter that you are going to use, raise the outlet of that hose up to the level of the top of the tank water, and time how long it takes to fill the pitcher. The important point is making sure you are simulating the level difference between the top of sump and top of tank so that your head is equivalent, and using the same diameter return hose as this also affect the pump flow rate and is not accounted for the in RC calculator either. Putting more flow through a smaller hose does not linearly increase the actual flow rate, pressure increases and thus so does friction, and it is significant. The size of your return line does not affect head which is why this technique works.

The RC calculator works as a general guideline if you ignore pump head loss and design the overflow such that the total length is what they suggest, as the head loss realized and the reduced flow of a notched overflow box tend to cancel out. So your system will work IF you ignore these losses, but what you end up with is less flow than you thought you were getting, leaving feeling generally ripped off or stupid when someone points out that you're not getting 700 GPH through your overflow, but instead getting more like 350. This prompts you to go by more power heads than you thought you needed, which adds more heat to the tank and ups your electric bill, could cause heat problems, prompting the purchase of a chiller, and potentially causes wife troubles as your money continuously floods from your bank account to your tank account. hey that's pretty funny I just came up with that.

Anyways...HTH

 

worked for me just now

 

no, watch the video again. Smartphones give off polarized light. a polarized lens will block all the light if turned to the right spot. tempered glass 'scrambles' or de-polarizes the light, so if you put a piece of tempered glass between your phone and a polarized lens, you won't be able to block the light by turning the lens since the light from the phone is no longer polarized.

you could do the same thing with a flashlight and 2 sets of lenses, one over the flashlight (to polarize the light) and one on the other side of a piece of tempered glass. The glass would de-polarize the flashlight's artificially polarized light. Pretty cool trick.

 

I am not seeing the sketch...

 

I don't have a smartphone. can't see it on my pc

 

I think it would have been more accurate for AJ to have said "some people", because there are some people that don't feel they should make much of an effort to help out a non-club member.  I, as well as many others, do not subscribe to this philosophy - I think that kind of thinking is negative, counterproductive, and drives people away.  That being said, it is far from extortion.
Personally I'll help just about anyone out.  I would hope that they appreciate the effort and would consider paying the club membership dues.  But ultimately, it's their choice.  I'm not going to get completely bent out of shape if someone chooses not to join, and I'm not going to get hoity-toity because I paid $20 dues and someone else didn't.  After all, it's not like I'm a member of a friggin country club.  That's my philosophy: positive, productive, and inviting.
I think this thread exemplifies the fact that others ARE willing to help someone out regardless of club membership.  People are either going to see the benefit, or they're not.  Our only job as members is to provide them the option and let them decide what's right for them.  Trying to tell someone what's right for them or force them into a position where they feel they have to do something they don't really want to is completely counterproductive if you ask me.
But let's say that someone has an emergency and needs help.  Someone steps up to the plate and visits their home and helps them out.  They would have paid an LFS or contractor through the nose for a visit like that.  At that point I would think someone would understand that $20/year is nothing compared to the benefit they just got from a local group