Hydroponic Submersible Pumps
Water volume and how high you need to pump it
When in doubt, buy a pump with higher GPH than your think
Flood and Drain systems (Ebb & flow)
First you are going to want to know how much water your going to need to pump. It doesn’t mater what your using for the growing chamber, or how many of them you have, it’s the same simple process to calculate the water volume. If the container doesn’t have the gallon size written on it, just fill it up with water to the water level you want, but just make sure to keep track of how many gallons it takes. That gives you the water volume you need to fill/flood it.
After you know the water volume you need to pump, you will need to figure out how high it will need to pump it above the water line in the reservoir. For that you will need to know where your going to be putting the system and reservoir. As an example, if your putting the system (growing chamber) on top of a table, and the reservoir on the ground near it, the system will probably be somewhere between 2 and 3 feet above the water line in the reservoir. If your mounting the system along a fence or wall, the height could be much different. Knowing how high the pump will need to pump the water up from the reservoir is a very important aspect of picking a pump (probably even the most important thing to know).
Precision on deciding a pump for drip systems is tricky. Decide what you want – giving the plants a gentle soaking that can last 15 min, hours, or even 24/7. You’ll want to make adjustments to your moisture level using a timer on your pump.
The more plants and drippers you have, the more pressure you need. Most pumps don’t give pressure ratings (psi). The the higher the head height, the higher the psi.
water depth and flow rate are the biggest factors in the GPH in your NFT system. E.G. – water depth of 0.25in , 4in wide tube, 10ft long tube will hold about 0.5 gallon of water. Recirculate 0.5 gallons of water every 5 minutes = 6 GPH / tube.
Increase flow rate or changed the angle? Recirculating that 0.5 gallon of water every 2.5 minutes, then your are pumping 12 GPH. Tube length isn’t that important, and wont affect the flow rate or GPH you need to pump.
There are two types of aeroponic systems. True aeroponic systems use high pressure sprayers, 60-90psi. Most people refer to low pressure spraying systems as aeroponic systems too.
True aeroponic systems don’t really use a water pump.
Low pressure systems use standard submersible water pumps, but still need a good amount of water pressure or the water won’t spray properly from the mist heads. The more mist heads, the more pressure. You will want to look at head height of the pump and choose a pump with a higher head height rating which would indicate a higher pressure pump.
The exact amount of pressure varies greatly from system to system and plant to plant, general rule is to keep water making contact with roots, without them moving as movement could mean the pressure is too high and actually damaging the roots. Smaller droplets or mist is better and easier for the roots to uptake.
What you should know about water pumps for Hydroponics
Once you have calculated the minimum number of GPH you need for your system, finding a pump is pretty easy. We recommend you choose a pump that pumps at least twice as much water as the minimum GPH you need. This allows flexibility in your setup, future changes, and the possibility of coming up short and needing to purchase another pump.
You can easily reduce the flow of your pump. Most pumps have a flow restrictor built in that slides/pivots over the opening to reduce the water inlet opening size.
If you don’t have a restrictor slide, install a ‘T’ connector in the tubing to your plants, just above the pump and still inside the reservoir. Leave one half of the the ‘T’ open so water goes back into the reservoir. If you want more control of the ‘T’ method, install a valve on the end that returns to the reservoir and open and close as needed.
GPH – Gallons per Hour
All pumps will have maximum GPH listed. If there is a a range listed like 300-500, there are usually two different size adapters. The smaller adapter will give you the lower max GPH, larger adapter – higher max GPH. * max GPH is only at ground/water level.
The higher up the pump needs to move the water, the lower the actual GPH output – called “Head Height.”
Some pump manufacturers will display a chart or list the max GPH at various heights.
Please keep in mind GPH = Gallons per Hour. You will more than likely, at some point, need to know Gallons per Minute for most hydroponic systems. Divide by 60. You don’t want it to take an hour to flood your system, you’ll want to flood in a few minutes.
E.G. – You need 50 gallons to flood your system, and you want to flood within 10 minutes, 60min / 10min = 6 then 50gal x 6 = 300. That’s equal to 5 gallons per minute, and/or 300 GPH pump minimum.