Aero pumps PLEASE HELP

So I am trying to figure out which pump will best satisfy my needs for a very large aero system. Of course cool reservoir temps and pump reliability are of the utmost importance. When I started this project (first aero) I thought that external pumps were really my only option for keeping reservoirs cool but now I'm starting to think otherwise. The fact that I saved money and went with only 1/10 hp chillers also made me think external was the way to go.They are keeping my 70 gal reservoirs between 65-68 when they are totally full and between 60-65 when they are not completly full. I have been using 1/2 hp cast iron pumps that push 720 GPH.
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_7738_7738
They work great especially for the price but they only work for about two weeks then I have to replace them. The replacements are free but I have to drive an hour away to get them. Needless to say I am not sleeping that well with this current pump situation. So I have looked at replacing them with these more expensive stainless steel 1 hp american made pump by Wayne.
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200311411_200311411?cm_sp=Customer driven-_-Recently Viewed-_-Category Page
But now I am starting to think that 1/4 or 1/3 hp sump pumps are really the way to go as far as price and most importantly reliability. Plus a 1/4 hp sump pump pushes more gph then a 1 hp external pump(don't ask me why?). My only problem would be heat. But if cycle timers are set to run 2 minutes on and 5 minutes off I am starting to think that two minutes on doesn't really give the pump time to heat up. That is what I really need to figure out. Earl and all experienced areo growers please help! How do you guys set your cycle timers not only to most benifit the plants but also the life of your pumps and temp of your reservoirs. I've heard shorter cycles are better but I feel like 1 minute on 2 minutes off puts excessive wear on your pump. Has anyone found a cycle timer that allows for different day and night settings. My CAP cycle timers do not have this feature which sucks. My last question is how do I calculate what the ideal GPH would be for the size of my system? So experienced aero growers help me get a better nights sleep. External or Sump pump? How many GPH? Do you like that Wayne pump? Or can you reccomend a very reliable sump pump.

How many spray jets ?
What is the GPH of the spray jets ?
add up the numbers.

I use the mag drive pumps for these reasons

1 they are very quiet.
2 they can operate continuosly(no duty limit)
3 they can operate regardless of flow.
In other words they don't need to flow,
that means if you have oversized your pump
there is no detriment.
4 they are so simple and never never fail.
5 a replacement impeller is $15 if you let it get clogged with roots.
6 they are cheap and available on ebay

Keep a spare $15 impeller
and you will never be down
more than 15 minutes.

If you must go with another type of pump
I can not offer any help,
as mag drive pumps are all I use.

Along with "flow rate,"
a pump's "head pressure"
(or more accurately "pressure-head," "shut-off head," or "shut-off pressure")
is a term often used in pump literature
to describe how powerful a pump is.

"Flow rate" is simply the volume of water a pump can move
during a given amount of time.

Pump flow rates are usually expressed in gallons per hour
or gallons per minute.

"Head pressure" on the other hand is more complicated.

"Head" may be simply defined as any resistance to the flow of a pump.

When pump manufacturers list the head pressure,
they are referring to the vertical discharge pressure head.

Described in very simple terms, a pump's vertical discharge "pressure-head"
is the vertical lift in height (usually measured in feet of water)
at which a pump can no longer exert enough pressure to move water.

At this point, the pump may be said to have reached its "shut-off" head pressure.

When you look at a flow curve chart for a pump,
the "shut-off head" is the point on the graph
where the curved line becomes horizontal
as the flow rate at that point is zero.

The higher a pump's head pressure,
the more powerful the pump.

To use flow rate and head pressure to help you select a water pump,
you need to know how much water you need to move through your system.
( the volume of your spray jets and filters combined)

And how much resistance (head) the pump will encounter
as it moves water from point A to point B.

For any pipe system,
in addition to the friction losses,
there are additional losses called minor losses.
(although in our case these losses may far exceed the friction loss).

These losses arise due to the pipe entrance and exit,
sudden expansion or contraction,
bends, elbows, and other fittings, filters, or valves, etc.

What this means is that the amount of friction created by the fittings
is the same as that of the specified straight pipe.

We can add this length of straight pipe to the total pipe length in the system
and compute the friction loss.

Engineering data

Pump Head Loss Calculator

.

If you are not trying a high pressure aero system, then you'll definitely want to go mag drive for all of the reasons that Earl has mentioned and more.

If you are running true misters, you'll want to look into FloJet Pumps. They are inline and self priming with an integrated check valve.

The downfall of mag-drive pumps is they do not integrate a check valve (though you won't likely have problems with back-siphoning in an aero)
and they are not self priming - they must be lower than the res or submerged, and will not prime if there is significant blockage after the pump.


I do disagree with Earl about over-sizing a mag drive pump. It will run more smoothly and cooler if properly sized and/or it is displacing the proper amount of water.
"[SIZE=-1]Excessively small delivery flows or closed valves in delivery line [/SIZE][SIZE=-1]In this case, the liquid in the pump will gradually heat up. Depending on the specific medium, this may cause evaporation of the liquid between the bearings, and dry-running of these bearings, or thermaldestruction of the plastic lining. Consequently; overheating will occur immediately if the pressure-line valve is completely closed. [/SIZE]
[SIZE=-1]Protection methods: [/SIZE]
[SIZE=-1]Motor load monitor, flow-meter, by-pass from pressure line (upstream the pressure valve)." [/SIZE]
This is why a lot of systems use a "pump bypass" that will allow excess flow to run back into the res. A simple tee and a ball valve allow you to tune this in.

You can use the resources that earl posted to calculate what you need, but the first part of his post basically covers it:

(# of sprayers) * (GPH rating of sprayers) = (minimum pump GPH rating)
but this doesn't account for loss, so I'm personally thinking on adding 20% so:
[(#of sprayers) * GPH rating of sprayers)] * 1.2 = (minimum pump GPH rating)
The lift after the pump is definitely one of the biggest factors, but as Earl pointed out, for our application, this is usually pretty small and the "minor losses" are usually expressed.

This is only a theory for now. I'll be fabricating a couple aero systems soon and will be testing this theory.

I'm also going to try to experiment with adjustable drip manifold to try to dial in individual sprayers.

I think that generally, you're better off using an oversized pump and compensating with a bypass.

Ok thanks Earl and AeroKing. What would be the GPH rating for the cheap 55 cent 360 degree ezclone sprayers thats what I'm using same as Earl I think. AeroKing what sprayers do you use? I'm leaning toward the mag drive pumps. The noise alone would be reason enough to avoid getting more loud external pumps. I just need to know how much heat you think they will add to my reservoirs and what length cycles would be best for my plants and avoiding too much heat from the pump?

I think I would want to use the the mag drive pm 12 (1200gph) or the mag drive pm 18 (1800gph). They look to be of higher quality then mag drive pumps I've seen in the past.

mount you pump outside of your res that should help with temps

Earl what did you use to insulate your reservoir?

R-13 fiberglass and mylar space blankets
attached with spray-on contact cement.

Hey Earl the mag drive pumps will work with an external set up?

Yes you can.

You need to purchase bulkhead fittings
to have a water tight connection.




I have all my pumps externally mounted.

How much louder does that make the pump?

The only sound they make
is when the timer turns them on,
there is thump or click, as the lines fill with pressure.

The only way I can tell if the pump is on
is to look at the light on the Cap-art timer,
or put my hand on the pump, and feel it working.

Looks like I'm going with the mag drive pm 18 (1800gph). Hey Earl what is the gph rating for regular ez clone sprayers?

Aeroponic microjet 360º sprayer

5 to 30 psi
produces 15 gph @ 5 psi
to 26.5 gph at 30 psi.

Here is a link for you
http://www.emeraldelectronic.com/store/prodpage5.cfm/CategoryID/20000/SubCatID/1851/pstart/101/file.htm

GPH does not really matter if you have enough pump.

I bet the 1800 will work great for you.