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pump power


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Old 04-11-2012, 06:38 PM
miracledogg miracledogg is offline
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Default pump power

Is there somewhere a formula how to calculate the power a pump

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Old 04-12-2012, 03:01 AM
GpsFrontier GpsFrontier is offline
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What do you mean? Are you trying to figure out the energy cost? Or how strong a pump you'll need?
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Old 04-12-2012, 04:35 PM
miracledogg miracledogg is offline
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Originally Posted by GpsFrontier View Post
What do you mean? Are you trying to figure out the energy cost? Or how strong a pump you'll need?
I mean how to calculate how strong a pump must be in gph or L/min and how many energy it will use in ampere at 120 volt
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Old 04-14-2012, 05:39 AM
GpsFrontier GpsFrontier is offline
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miracledogg
Well, how strong the pump should be has many factors. There are 2 ratings on pumps that are important. The most important is the head height (the maximum height the pump can pump the water to). This is basically the pressure. Once the water reaches the maximum head height, it equals the pressure the pump can push the water out. Thus the water flow stops because there is to much back pressure in the water tube. The other rating is GPH (gallons per hour). the gph rating changes depending on how high the water is being pumped up to. The maximum gph is what the volume the pump can put out at zero feet high, the gph you get at 3 feet high will be lower than at zero feet high. Most pumps have a chart that tells you the gph at different heights.

Beyond that it just comes down to the type of system your using, as well as all the variables on how you built your system. How high the pump needs to pump, where the reservoir is in relation to the system, how many gallons it takes to flood, etc.. Not to mention how fast or slow you want it to work/flood & drain/drip. So there is just no chart that can take into account how you built your system. Basically all you need to do is figure out how many gallons the system will take to completely flood (just a educated guess guess will be fine), as well as figure out how high the pump will need to pump the water. Then just get a pump that will be able to pump that much (or preferably more) water at that height (or preferably higher). If your planing a drip system, then how many gallons it takes to flood wont be a factor. But how many plants your running the drip lines to (and the head height) will, as well as the size lines you choose to use. But typically a drip system wont need as high a GPH rating compared to running a flood and drain system, unless your running the line to a relatively large number of plants.

As for how much the electricity will cost you to run the pump. Well that's easy. Just figure out how many watts the pump is. It usually says on the box, if not multiply the volts by the amps to get the watts. Then find out how much you pay per kilowatt hour, the rate you pay will be on your electric bill. That's all you need to find out your estimated cost to run the pump (or anything for that matter). Here is an online Electricity Cost Calculator. Just fill in your rate, watts, and how long you want to use it, and click calculate. Play around with changing the watts and running time (just keep the rate you pay the same as what you actually pay).
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Old 04-14-2012, 06:44 AM
miracledogg miracledogg is offline
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miracledogg
Well, how strong the pump should be has many factors. There are 2 ratings on pumps that are important. The most important is the head height (the maximum height the pump can pump the water to). This is basically the pressure. Once the water reaches the maximum head height, it equals the pressure the pump can push the water out. Thus the water flow stops because there is to much back pressure in the water tube. The other rating is GPH (gallons per hour). the gph rating changes depending on how high the water is being pumped up to. The maximum gph is what the volume the pump can put out at zero feet high, the gph you get at 3 feet high will be lower than at zero feet high. Most pumps have a chart that tells you the gph at different heights.

Beyond that it just comes down to the type of system your using, as well as all the variables on how you built your system. How high the pump needs to pump, where the reservoir is in relation to the system, how many gallons it takes to flood, etc.. Not to mention how fast or slow you want it to work/flood & drain/drip. So there is just no chart that can take into account how you built your system. Basically all you need to do is figure out how many gallons the system will take to completely flood (just a educated guess guess will be fine), as well as figure out how high the pump will need to pump the water. Then just get a pump that will be able to pump that much (or preferably more) water at that height (or preferably higher). If your planing a drip system, then how many gallons it takes to flood wont be a factor. But how many plants your running the drip lines to (and the head height) will, as well as the size lines you choose to use. But typically a drip system wont need as high a GPH rating compared to running a flood and drain system, unless your running the line to a relatively large number of plants.

As for how much the electricity will cost you to run the pump. Well that's easy. Just figure out how many watts the pump is. It usually says on the box, if not multiply the volts by the amps to get the watts. Then find out how much you pay per kilowatt hour, the rate you pay will be on your electric bill. That's all you need to find out your estimated cost to run the pump (or anything for that matter). Here is an online Electricity Cost Calculator. Just fill in your rate, watts, and how long you want to use it, and click calculate. Play around with changing the watts and running time (just keep the rate you pay the same as what you actually pay).
GpsFrontier
Thanks for your reaction
to be more specific
i want to do nft
head height is about 2 m (from the bottom of the tank to the growing gutter)
horizontal distance to the last growing gutter is 24 m
to flow the system i need 450 gallons
i'm a the tropical environment
and something else
how can i calculate the oxygen pump,the air flow for these specs
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Old 04-16-2012, 03:37 AM
GpsFrontier GpsFrontier is offline
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miracledogg
Going by your numbers I would say you are looking for a pump that has a minimum of 450 GPH at 2 m (6 feet) head height. But if it were me I always go bigger for two reasons. First, that's only a minimum requirement, and actual results may vary. Second, is it's quite simple to reduce water flow if the pump is to strong. You may also want to expand the system in the future, and/or use it for a different one all together. If 450 GPH is the goal at 6 feet high, I would be looking for a pump that could do twice that as a minimum.

With that said, it sounds like you plan to build quite a big system. That has me wondering how you came to your figures. If you have 24 m (75 feet) of gutters, and if they were spaced 1 foot apart, that would be 75 growing gutters. 450 gph divided by 75= 6 gph each. Then 6 gph divided by 60 minutes equals 0.1, or about a cup and half (12 oz) per minute water flow through the NFT gutters. I have never done a NFT system but that seems kind of low to me, but may be fine.

I also don't know if the spacing is what you have planed. If your growing lettuce, and you offset the plant spacing in the gutters, they can be be spaced much closer. Like about 6 inches, doubling the amount of gutters in the same space. But at the same time cutting the water flow in half to each from 12 oz a min, to 6 oz a min. So I have no idea how you came to the figure 450 GPH. But that dosen't mean its wrong. Just that I cant compare what I would do in the same situation, simply because I don't really don't know the specifics of your situation.

I should also mention that if you plan to run such a long water line, you'll want to make sure you don't loose water pressure from one side to the other. That can be done a few ways. But if it's not taken into account, the gutters first in line will get most of the water flow (to high), and those at the end will get very little water flow (to low).

Quote:
how can i calculate the oxygen pump,the air flow for these specs
You cant. Again there are quite a lot of variables to consider. First and foremost is your system design. Second is your water temperatures. I also have no idea if you are trying to pump air to each NFT gutter, or just aerate the reservoir. Not to mention how many plants you plan, what type they are, or even how big they will/can get. All of witch will play factors in the oxygen saturation point of the water in the first place, as well as how fast the plants will use it up in the second place. But the best rule of thumb is get as much oxygen to the roots as you can, there's no such thing as too much oxygen to the roots in my opinion.

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Last edited by GpsFrontier; 04-16-2012 at 03:49 AM.
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