# Sizing a Pump for Aquaponics or Hydroponics

## Variables For Calculating Pump Size *

Figuring out the correct size of pump for you aquaponics or hydroponics system is something beginner growers run into when starting out. In order to determine the best pump for your system, you’ll need to analyze a few variables:

- gallons that need to be moved per hour
- head height

Let’s take a look at each variable, then how to combine them in a way that will tell you what size of pump you need.

(If you start feeling overwhelmed at any point during this post, just pick up a phone and call one of our super-friendly team members at our office: 307-766-6538. Rikki and Amy have got your back!)

## How many gallons per hour? *

Pumps will almost always have a Gallons Per Hour (GPH) rating that tells you how many gallons of water that pump will move every single hour.

Obviously, places that favor the metric system will use liters per hour. (You can use the same equations, just remember that if you change one unit you have to change all of them.)

Figuring out GPH is easy.

** In hydroponics**, you want to run two gallons of water through each tower every two hours. This means that the number of gallons is essentially the number of towers, times 2, then divided by 2… or just the number of towers.

Of course, you’ll also have a bit of extra water in your sump- a good rule is to add fifty gallons for the sump. So, you end up with a gallons per hour (GPH) for hydroponics equation like this:

**In aquaponics**, you’ll want to run seven gallons of water through each tower every two hours.

Since you’ve got the fish tanks as well, you also need to factor in the fish tank gallons. You’ll also be turning over the fish water every two hours, so the gallons per hour for aquaponics equation looks like this:

For example:

So, let’s say we have a 100 tower system. Thinking about our minimum recommended amount of water we should be moving, we’ll need to move 50 gallons per hour in order to turn our entire system volume over at least once every two hours. Then we’ll add on 50 gallons for a sump tank.

That means we’ll need a minimum of a 100 GPH pump.

Boom. One factor done. Keep your GPH number on hand; next we’re talking about head height.

### Pump Height Efficiency

Because almost all aquaponic or hydroponic growers need to move water upwards, you’ll need to also understand how efficient your pump is a different heights. Even if you’re still using a traditional horizontal grow bed model or NFT, as opposed to a high density, productive powerhouse like ZipGrow towers**,** you’ll still need to move water vertically from your fish tank to your beds or troughs.

To compensate for the height, we use a measurement called head height.

## What is Head Height? *

**Head height is the distance between the top of your grow bed (or ZipGrow tower) and the top of the water in your tank.**

You won’t even need to do a calculation for this. Just measure the length between your pump and the top of your irrigation (which is probably the drip lines above your towers.)

For example, If you have a pump at the bottom of your sump, which is 4 feet below ground level, and you’re irrigating your towers 5.5 feet above ground, your head height is 9.5 feet. Simple, right?

## Combining GPH and Head Height *

See the chart above? That’s you’re cheat sheet, and most pumps come with a chart like this that matches their strength specifically. (Make sure you’re using the right chart for your type of pump. Inline pumps and submersible pumps function completely differently.) Using the GPH you calculated and your head height, find the pump that matches your needs.

Usually pump efficiency at different head heights is almost never a linear relationship (again, check out the example on our pumps).

## Other Important Considerations *

### System Variance

When choosing a pump, remember that our recommendation of turning over your entire system volume at least once per two hours is a *recommendation. *If you shoot a little long, or fall a little short of this recommendation, everything will probably be just fine.

Just remember that every aquaponics or hydroponics system out there varies considerably. Whether the it’s the plumbing, system design, grow media, etc., every system is different and required GPH can vary because of it.

**The important thing** to remember is that you are exchanging your water fast enough to maintain a good level of dissolved oxygen in your system. Try to avoid those lethal anaerobic zones in grow beds or towers.

### Pump Efficiency

When researching GPH and various head heights for your own application, remember that you’ll be moving water through what could be quite a long length of hose.

That said, the further your system volume travels, the lower your pump’s efficiency will be, and that could mean a decreased GPH or overall system performance.

While it’s possible to do the efficiency calculations here, it’s much more simple just to eyeball it and calculate anywhere from a 15% to 30% loss of efficiency (this of course depends on your plumbing and system design).

## Pumps for Aquaponics or Hydroponics *

### Questions?

Post them to the comments below and be sure to share this content if you’ve found it helpful!

I saw one other comment only two days ago about whether the volume of water in the calculations is for the fish tank or whether it includes also all the water in the deep raft, sump, and other parts of the system. Also, can the pump efficiency be radically reduced by hose or pvc that is too small in diameter, for instance all else being equal, would you get a substantially lower turnover rate with 1.5 inch pvc lines compared to say 3 iinch pvc?

Can you share some info on sales?

How to make an income from this life style of farming.

Hey Dan, could you get a little more specific with your question?

How many gallons per hour for each gallon in the system?

e.g. 6, 5 gallon buckets – how many gallons per hour – how strong a pump?

For a small system, you need to turn over your entire system volume at least once every two hours. That tells you how large your pump is, etc.

For a 100 gallon system, you need a pump that moves a minimum of 50 gallons per hour.

You’re saying opposite things here- For pumping…Is it 2x an hour or once over 2 hours? These are very different flow rates.

Hi Sylvie, it’s once every two hours.

Okay, semantics needing some clarification— in the article it says specifically IN BOLD “at least once every two hours.” Which is it? Twice an hour is 4x that amount…..

Hi Bo! Great catch – I’ve changed it now to reflect the CORRECT answer: Turn your entire system volume over once every two hours.

Hey Chris, great information as usual! This is the first time I think I have heard anyone say move the entire system water once every hour. That makes it easier to understand. Thank you again for more easy to follow info!

You’re welcome, Steven! So glad you’re finding our blog a valuable resource.

This article is great. How did you learn all this information though? I find it hard to remember even half of what’s written here. Keep up the good work!

Hello friend,

Very help full blog for the “Sizing a Pump for Aquaponics or Hydroponics.” Nice impressive blog and Pump Efficiency, Gallons Per Hour, Pump Height Efficiency etc.