in this short video i'm going to give you some practical advice on the selection of a pump for
your nft system i'll also show you how easy it is to do the calculations let's do it there's only a
few parameters that's important in pump selection the first parameter is the amount of water that we
must move in a specific time period that can be in either liter or gallon per hour if we only need to
lift a small amount of water we can get away with a smaller pump and obviously if we need to lift
more water in a given time period then we need a bigger pump our second parameter is how
high the pump must lift the water and for that we use a normal measuring tape so we measure from the
lowest point that the water can be in the system up until the highest point where the pump must
lift the water next parameter to consider is the friction in the pipe and the friction in a small
diameter pipe will be much more than the friction in a larger diameter pipe so from this we can
learn that the larger diameter pipe will have less friction and it's much better to use than
a smaller diameter pipe another thing that will influence the friction of the water in the pipe
is the length of the pipe tere will for instance be a lot more friction in a longer pipe than in a
shorter pipe the first thing that's important when you want to buy a pump is the pump curve
now let's have a look at a typical pump curve now this is a typical pump chart that you'll use
in the selection of the pump there's two pumps indicated on this chart a ddf50 and a ddf-110
this is the characteristic curve of the ddf 50 and that one of the ddf110 on our vertical axis
we will have the head of the pump that's how high the pump must lift the water on our horizontal
axis we will have the flow rate and in this case it's indicated in cubic meter per hour now you
may ask we've got the height that we lift the water and we've got the flow rate but what about
the friction in the pipe how do we calculate the easy way for small systems is just to add 20% to
your height let's consider this very simple nft system nft system is a nutrient film technology
so it means the pump will pump the water up and just a small film of water will be at the
bottom of the pipe and the roots of the plants that in these holes in the nft system will then
reach to that water and that's how they will get their nutrients the flow rate in a single nft pipe
in a hydroponic system is normally between 10 and 25 liters per hour the slope for a nft system is
normally two to four percent that means it must fall two to four centimeters per meter length of
the pipe now we need to consider how high must we lift the water in the system and remember
it's from the lowest point that the water can go up until the highest point where the pump must
take the water so it will be from this point the absolute lowest point that it can go in the sum
if you think your point is a little bit lower then you move your measure from there
up until the highest point the highest point that the water must be lifted
not the highest point in your system but the highest point where the water must be lifted to
this will give us our head that's the first thing that we must calculate
in this example we've measured this from there to there and we found that it's 1.5 meters
in order to compensate for the friction in the pipes we're going to add another 20% to that head
so 1.5 multiplied by 1.2 in order to add the 20% will give us 1.92m so that's the head
that we'll use in order to select the pump for our example let's use 15 liter per hour
and let's say we've got 100 of these nft pipes so what that will mean is we will take 100 so
we've got 100 of these nft pipes we're going to multiply that by 15 liter per pipe so that's 1500
liter per hour so we've got our two parameters now 1500 liter per hour is our flow and 1.92 meter is
our head by adding 20% to our measured head we've also compensated for the friction in the pipes
yes now let's use the values that we've got in order to select one of these two pumps so we've
got 1.9 meter head and 1 500 liter per hour flow rate so 1 500 liter we'll find here on this line
and then 1.92 should be somewhere around there so we'll just follow that so that will be our
operating point with those parameters we can see that the bottom pump the ddf50 will not be
able to deliver enough water at that head let's have a look at 1 500 liter per hour
it will only be able to lift the water about 1.4 meters so that's not sufficient for us
so we must go for the bigger pump now the bigger pump will be let's see 1500 liters
will be able to lift it almost 2.5 meters high it is always better to select a little little bit
bigger pump than to go with a pump that will not be able to supply the water at the correct head
another tip that i can give you is that the pumps are more efficient towards the center of the curve
so in this area the pumps will be more efficient than in this area or in this area
so if your calculated results fall within this less if efficient area it will be better for
you to look for another pump it always better to go for a higher quality pump that may be
just a little bit more expensive remember in an nft system if your pump fails and you're
not quick enough to replace the pump then you will lose your crop another factor to consider
is the economy side of the pump some pumps may lift this amount of water this high and only
use say a hundred watt higher hours another pump will do the same work and maybe use
300 watt hours so the economy side of the pump is also important some of the modern pumps got
variable frequency drives inside the pump and are more efficient than other pumps on your screen
right now you'll find another video that may also help you in your journey thank you and bye