So I've seen this chart everywhere:
www.reef2reef.com
I've also seen a zillion discussions of that chart that I find very confusing.
I just want to know: If I have a full siphon drain line that goes from an external overflow box down about 3' to the sump below, do I want to use the gravity number, or assume some amount of pressure?
The discussions I see talk about how depending on your drop length (for example), you'll get a lot faster than the GPH given for gravity only. Huh? How is that possible? What else besides gravity is at work here? I'm not actively pushing water down my drains with a pump, for example. There is a return pump, of course. But that just shoots water up the return pipe. It's not pushing water down the drain pipes. Water is simply falling down the drains. Full siphon or no full siphon, there is only gravity.
Or is that the wrong way to think about it? Is that chart trying to say that gravity means how fast water falls off a cliff thru a given pipe size, but if there's a full siphon (a column of water running some length down a drain), then you should consider that your water is somehow under pressure by virtue of the weight of the water column that forms in the pipe (no such thing exists off a cliff/splash drain)? I guess that might make sense, but it makes my brain hurt somehow to think about what's happening to the water before it enters the drain pipe. I guess it's generally just not under pressure (well, depending on depth, etc. etc.).
3/4 inch full siphon drain gph?
Quick question, what is the max gph for full siphon on 3/4 inch pipe?
www.reef2reef.com
I've also seen a zillion discussions of that chart that I find very confusing.
I just want to know: If I have a full siphon drain line that goes from an external overflow box down about 3' to the sump below, do I want to use the gravity number, or assume some amount of pressure?
The discussions I see talk about how depending on your drop length (for example), you'll get a lot faster than the GPH given for gravity only. Huh? How is that possible? What else besides gravity is at work here? I'm not actively pushing water down my drains with a pump, for example. There is a return pump, of course. But that just shoots water up the return pipe. It's not pushing water down the drain pipes. Water is simply falling down the drains. Full siphon or no full siphon, there is only gravity.
Or is that the wrong way to think about it? Is that chart trying to say that gravity means how fast water falls off a cliff thru a given pipe size, but if there's a full siphon (a column of water running some length down a drain), then you should consider that your water is somehow under pressure by virtue of the weight of the water column that forms in the pipe (no such thing exists off a cliff/splash drain)? I guess that might make sense, but it makes my brain hurt somehow to think about what's happening to the water before it enters the drain pipe. I guess it's generally just not under pressure (well, depending on depth, etc. etc.).
