plumbing question

[Craig58]

tank-->drum-->drum-->pump-->drum-->drum?

Is that correct?

I think you want that could lead to complications. I'd keep it simple, gravity fed to drums and pumped back to pond, or pump to drums and gravity feed back to pond.

Sounds like you're attempting both? Maybe I got lost here?

Craig

 

[EVMIII]

This is what I am thinking.

Thanks

Bud

 

[Waterbug]

What did your calculations show?

 

[EVMIII]

Waterbug,

Using the calculator you linked (thanks), how does the math work when the water flowing from the BD will flow approximately 2' up hill to the prefilter. The prefilter can easily be made level with the pond water level. The pipe is going to be 15 feet long.

Simply thinking, up to the max capacity of the pipe, won't the pre filter tank be filled at the same rate that the water is leaving the tank because of gravity's desire to keep them level? If so, I can't them figure out the flow through the 3" BD pipe until I know how quickly I can get water through the drums?

What am I missing?

Bud

 

[Waterbug]

Using the calculator you linked (thanks), how does the math work when the water flowing from the BD will flow approximately 2' up hill to the prefilter. The prefilter can easily be made level with the pond water level. The pipe is going to be 15 feet long.

OK, the up hill thing...This is what I was trying to explain in post #18, I'll give it another try.

The calculator I gave only computes how much water will go thru a pipe only using gravity. It doesn't care about up hill, or down hill, just "drop". If you have a single length of pipe then up hill, down hill and drop are all the same thing. But you're looking at a single length of pipe, not the entire "pipe".

Here's a cut away view of a horizontal pipe with 90 degree elbows on each end, with some water inside. If we drop one end of the pipe water will start to flow out that end.

OK, duh, that's obvious. But consider this, what if I dropped the end just a hair? The pipe wasn't 100% full, so no water would actually flow out. No water would actually flow at all. It's only the surface of the water that matters when we talk about drop. I have to lower the surface of the water in one end to be below the surface of the water in the other end. It's true, to lower the surface I must first lower the top lip of the pipe below the surface of the water. Water does seek level, but not instantly. And what controls the speed? Pipe size.

Let be push this point further... What if I add a larger fitting on each end and add some more water?

Same deal as before. What if those fittings I added were 12" across or 12' across or 12 miles across? Nothing changes. If I drop one end water will start to flow out the lower end. As you've guessed by now one of those "fittings" is your pond and the other is your first filter tank. That's the "pipe", the entire system.

The point I'm making is the gravity flow calculator uses the drop from one end of a pipe to another. It's more accurate to say the calculator uses the drop from one "open end" to the other "open end" and even more accurate to say from one "water surface" to the other "water surface".

Back to up hill... What happens if the horizontal pipe goes up hill instead?

Nothing changes. If I drop the right end water will flow out exactly as before. Or I can drop the left side...now that "up hill" pipe could be considered a "down hill" pipe. Same drop = same flow. Like a Honey Badger, gravity don't care.

With that, back to your question...

Using the calculator you linked (thanks), how does the math work when the water flowing from the BD will flow approximately 2' up hill to the prefilter. The prefilter can easily be made level with the pond water level. The pipe is going to be 15 feet long.

The prefilter and pond can and should be at the same level, which is basically my 3rd drawing. If they're at the same level there is no flow once they even out.

Before, when talking about pipes, I could drop one end and water would flow. We can't do this with a pre-filter, it stays in place. We don't actually have to drop the filter, we only need to drop the water level. If we remove 1 gal from the tank about 1 gal will flow from the pond to the tank. Obviously this is done with a pump.

Post #23 explains the rest.

Trivia: I said we can't drop the prefilter, well that's exactly what a Cetus sieve does if you've taken a look at those. The floating weir is the "other open end" and it goes up and down as needed.

Simply thinking, up to the max capacity of the pipe, won't the pre filter tank be filled at the same rate that the water is leaving the tank because of gravity's desire to keep them level? If so, I can't them figure out the flow through the 3" BD pipe until I know how quickly I can get water through the drums?
What am I missing?

I'm not sure I understand the part in bold, but I'll go on...

You might be missing one of two things, time or pipe size. Given enough time the water level in both tanks will become level. Pipe size defines that time. The gravity flow calculator computes gals per second, time. If your BD pipe was 1/2" instead of 3" and your pre-filter was empty and you opened a valve it would take longer for the tank to fill, 1/2" pipe vs 3", obviously. The not so obvious part I think is that most people kind of get it in their head that a 3" pipe is huge, probably the biggest pipe they've ever seen and it can handle any amount of water a regular pond needs. But 1/2" or 3", it's all the same deal, just different numbers.


Beyond what's above...there are additional calculations that deal with pipe size, length of the pipe, number and kinds of fittings. These are friction loss calculations. Right now I'm just trying to get you into the ball park so I wouldn't worry about friction loss for now. I don't think friction loss is really going to amount to anything anyways. Gravity flow is the big one.

 

[EVMIII]

Waterbug,

Let me first say thank you for your patience. I must be learning because everything that you said makes sense to me. I couldn't get the drop concept clear in my mind; I was hung up on pipe elevation and drop. My drop will be zero so i can plan accordingly.

Let me try to explain my statement you bolded above. My concern was how long it took the water in each drum to flow through the media. Different media will create different resistance. If i go in with a 2" pipe in and out that should be equal, the media being the difference. How much slower will he water flow out than in? Based on my new thinking, once the system balances out it shouldn't matter, assuming all the drops are equal ( or at least factored in).

My thought with my set up above the pump at the end could pull about twice as much as a 2" pipe with zero drop (because I have two inch pipes feeding the final drum. Idea is to allow the strongest pump possible to maximize the water I can push to the returns.

I'll do some math on the calculator and should be able to get a good estimate of the flow and size pipe I can use. Thanks again.

 

[EVMIII]

Another quick question

I have a Anjon monsoon MS4000 that can be internal or external. Is there any advantage to putting in a little pump well beside the Skimmer as apposed to putting the pump in the Skimmer. I'm thinking its a good idea because of the potential electrical current issues. I have room and a 5 gl bucket the will work. Thanks.

Bud

 

[Waterbug]

Let me first say thank you for your patience. I must be learning because everything that you said makes sense to me. I couldn't get the drop concept clear in my mind; I was hung up on pipe elevation and drop. My drop will be zero so i can plan accordingly.

I still get confused by water. I have to consciously say to myself when reviewing these types of things "look close", "don't use intuition", etc. So easy to make a mistake. And because the next part is dependent on a previous part a small mistake can result in big problems. I'm currently working on a software app to do all these calculations, but won't be ready for awhile.

Let me try to explain my statement you bolded above. My concern was how long it took the water in each drum to flow through the media. Different media will create different resistance. If i go in with a 2" pipe in and out that should be equal, the media being the difference. How much slower will he water flow out than in? Based on my new thinking, once the system balances out it shouldn't matter, assuming all the drops are equal ( or at least factored in).

I see now. You're right to be concerned. In addition to water going thru media you'll also have the issue of media clogging. Both issues are dealt with the same way, an overflow on each tank with media. In general the overflow and outflow pipe are the same thing, just taking in water at the surface. With this media can be removed from flow calculations.

My thought with my set up above the pump at the end could pull about twice as much as a 2" pipe with zero drop (because I have two inch pipes feeding the final drum. Idea is to allow the strongest pump possible to maximize the water I can push to the returns.

I don't know your current thinking on pump size. Would be good to add that info on your diagram.

I'll do some math on the calculator and should be able to get a good estimate of the flow and size pipe I can use. Thanks again.

You can add the flow amounts to your diagram. Makes it easier to see issues, mistakes and helpful for anyone reviewing. Also later, if you have a problem it's easier to spot a possible problem.

You're welcome. Thank you for sticking with it, I know it's a brick wall. But after awhile, and you seem to be there now, you'll start to see these calculations as a very useful tool.

 

[EVMIII]

Get me back on track

If the pond is connected to a tank by a pipe. The top of the tank is a foot under the water level in the pond. Will this tank overflow continually until the water level in the pond drops a foot? The rate of this drop is dettmined by the flow rate/size/resistance of pipe?

I know I'm regressing, just help me refocus. Thanks again or the education.

 

[Waterbug]

If the pond is connected to a tank by a pipe. The top of the tank is a foot under the water level in the pond. Will this tank overflow continually until the water level in the pond drops a foot? The rate of this drop is dettmined by the flow rate/size/resistance of pipe?

Correct.

 

[Craig58]

Ok.. question.. In a set up as he is planning... why wouldn't you just use the largest pipe, (i.e. 3") to connect up the stock tank and drums?

In his case isn't his goal to maximize the flow to the final drum, (without impacting the filtering), so as to not run out of water in the final 5th drum and not starve the pump? Given that all drums/tank are level with the pond, they won't overflow. So at that point the primary objective is to keep the final drum filled.

Wouldn't using 3" pipe throughout give you the best of opportunity for that? How would going with a smaller pipe be of any benefit except to possibly slow waterflow through the filters to increase performance.

Craig

 

[Waterbug]

why wouldn't you just use the largest pipe, (i.e. 3") to connect up the stock tank and drums?

Bingo. If a person doesn't want to do calculations a reasonable choice is to keep the same pipe size thru the entire system. There are edge conditions however when splitting and joining flows, etc. The more complex the system the edge conditions can pile up, and this is a complex system simply by the number of tanks desired.

So going to 4" would be a better guess if calculations are skipped.

Of course this only lasts for as long as it takes for the builder to find out the number of parts needed and the huge bump up in component cost when you go from 2" to 3" or 4". Later, a person new to this, really starts to see the problem is much more than cost. Larger pipe is harder to work with, harder to get water tight welds, less space. When they see leaks they really start to understand why planning can be helpful. With some planning complexity can be removed, the build made easier, less expense (to build and fix mistakes) and more reliable.

My brother trained me in basic electrical. I kept asking him why not make every circuit 20 amp? A little more for wire and breakers, but that seemed like a small cost to me. They looked the same to me at the beginning, seemed to work the same. He tried to explain it but I couldn't hear it. After wiring 12 ga all day and then using 14 ga you see the difference.

All this number stuff seems complex to a lot of people...needless complexity. Well, obviously at the beginning stage it's always going to be easier to just start cutting and gluing. But if you take the job as a whole, if the goal is a functioning well working filter system and not just a bunch of barrels and pipes that maybe sort of kind of works then planning reduces complexity of the project as a whole imo. Virtually every profession uses this model. A home builder can certainly build a house without plans, but they never would because they know it would take longer and be more expensive. Just depends on what a person wants.

 

[Craig58]

So going to 4" would be a better guess if calculations are skipped.

Well yes but that would be a waste of money since a gravity fed 3" bottom drain would have little chance of keeping two 4" lines happy with water unless it's coming down from an elevated water tower. But not in a leveled tank system.

I understand your point of it being somewhat more difficult but the PVC stuff is fairly simple to work with now. Using primer and solvent glue, leaks should not happen. Especially when the gravity fed lines are not significantly pressured. I'm not sure there is much difference between working with the 2" vs. 3". Maybe 2" to 4" yes. Some of the bulkhead fittings needed for the tanks can get expensive relatively speaking.

BTW: I upped my overflow to a 1" line on the new pond. Not quite enough using your calculations but the 2" was a bit to obtrusive. In the formal pond design I have, an overtopping will have little affect. The grading around the pond should channel any significant overflow away from the pond. There really isn't anything outside the pond to be damaged or altered by water flow and I'm pretty comfortable that any risk of the liner floating is pretty slim with the way the water drains from the pond when overtopped.

Craig

 

[Waterbug]

Well yes but that would be a waste of money since a gravity fed 3" bottom drain would have little chance of keeping two 4" lines happy with water unless it's coming down from an elevated water tower. But not in a leveled tank system.

Well Craig, I know you think you just know this stuff just by your gut and you have no need for numbers, science and such. Me, I don't know for a fact that given all the fittings, the splits, the merges, different pipe locations that a 4" pipe isn't needed. And who knows, you could be right. But lets not confuse luck with knowledge. I prefer to do the calculation rather than rely on your gut if you don't mind too much.

 

[crsublette]

WB, what do your numbers show?

It appears to me the 3" BD determines the initial flow. After static/dynamic head loss and friction loss, then the flow rate would never warrant a pipe above 3" assuming we're talking about gravity flow at pond water level. I am sure there are people that put 7+2 in a calculator to make sure it's 9, but this seems like common sense to know that without using a calculator; I definitely can be wrong. Reduce head and friction loss would be the only reason to go bigger than 3" after a 3" BD gravity flow at pond level, which going bigger can be a significant improvement depending on fittings.