True Pump Flow Rate vs the Rating

[koikeepr]

The wattage doesn't have anything to do with it. Wattage is power consumption--not ability to move water. There are pumps that have very low wattage ratings, that can move vast amounts of water. And there are pumps with very high wattage ratings. External pumps typically fall into the former category. They are very efficient for what they can do. With a 4500g pond, you really need a fairly large pump, and you would be better off with an external IMHO. At a certain point with larger ponds, a submersible doesn't make sense--and with 4500g, I think you crossed that line a while back.

I have a pump that moves 7200gph on my pond, for example, and it only uses 404 watts. That makes it very efficient for what it can do. My pond is basically the size of yours.

Can you exchange your submersible for an external with them.

 

[twinclouds]

Is he claiming you've got more head in the system than you realize, or admitting the pump doesn't meet their advertised specs? Or is he just slipping the issue and not addressing why you're not getting the flow you'd expect based on their chart?

I think what is the last. He implied the first but he cannot really say that because all other pump, v3900 and Pro4500 meeting can achieve the flow rate according to the head height I calculated. Of course he cannot admit they don't meet the spec. because there are liability consequences, but he also said even if I replace the pump, I cannot get better results. I think he is slipping the issue. I attached the reply below:

"If you would like to replace the Aquasurge 5000 with another, you can, but we would expect the same results. We are confident in our manufacturer’s specs and have had no known issues in regards to the products specifications. The Aquascape 4500 pump will pump a higher volume than the Aquasurge 5000 in a lot of applications. The advantage to the Aquasurge is the electrical efficiency. If you are not satisfied with the flow rate, I recommend switching back to the 4500. Replacing your current Aquasurge 5000 with another one will not provide a higher flow. That is determined by your application.

- Aquascape Tech Department
"

 

[twinclouds]

The wattage doesn't have anything to do with it. Wattage is power consumption--not ability to move water. There are pumps that have very low wattage ratings, that can move vast amounts of water. And there are pumps with very high wattage ratings. External pumps typically fall into the former category. They are very efficient for what they can do. With a 4500g pond, you really need a fairly large pump, and you would be better off with an external IMHO. At a certain point with larger ponds, a submersible doesn't make sense--and with 4500g, I think you crossed that line a while back.

I have a pump that moves 7200gph on my pond, for example, and it only uses 404 watts. That makes it very efficient for what it can do. My pond is basically the size of yours.

Can you exchange your submersible for an external with them.

Hi,
I agree with you that pump could be more efficient, i.e., for the same power consumption they could pump more water. This is the case of external pumps. However for submersible pump, it appears to me that it would be very difficult to achieve the same high efficiency. At least I have not find one yet.
As for the external pump, since the pond is designed for submersible pump, there's a few things I need to understand before convert it to external pump. Maybe you can help.
Firstly, I would like keep the pump to be above ground and not too close the fall. In such a case, the water need to be first go up to the pump then going down again to the ground. The water will be need to go up again to the fall. Not sure it will lost too much pressure. Second thing is how to hide the pump. It looks like the artificial rock will be a good way to cover it. However, I don't know heat dissipation will be a problem. Secondly, The third issue is choice of pumps. Do I need a self prime pump or a simple one. Your help and suggestions would be greatly appreciated.

 

[koikeepr]

External pumps are made to push water, and not pull it. They are not as effective when above ground--you want an external pump on the ground next to a pond below water line so that it receives a flooded suction of water.

You could have the same effect, for example, if you had a filter barrel that was gravity fed from your pond and then the pump sat next to the filter and received water flow from the filter. The pump doesn't care if it's below water line on a pump or a pond--it doesn't know the difference.

Pumps are very easy to hide with an irrigation box or a mock rock or other item such as that. A pump with a priming pot on front is what I would suggest, as that priming pot/leaf trap catches anything that may happen to enter and prevents it from going through the pump. For example, last week I happened to notice that two large frogs were in my leaf trap sadly. However, had I not had the trap in front, the frogs would have been sheared to smithereens by the pump and then would have gone into the filter and pond. Or worse, the pump could break and impeller leg or something. A leaf trap is great insurance, as far as I'm concerned, and usually ads only $50 bucks the pump. You can even buy them on Ebay pretty cheap.

I would recommend a Sequence pump to anyone. DoDad here on this site can be PM'ed for a price, as his quotes will be better than what you see anywhere online. Sequence are workhorses and use very little power for what they do.

 

[Otter]

Firstly, I
would like keep the pump to be above ground and not too close the fall. In such a case, the water need to be first go up to the pump then going down again to the ground. The water will be need to go up again to the fall. Not sure it will lost too much pressure.

Assuming the inlet and out let are in the same place, ups and downs don't create any more head than horizontal curves. But any time you go up and then down instead of down and then up, gasses can be a problem. Of course the pump would send them back down the pipe, but if the pipe went very far down, they might come back to the pump instead of going all the way out the falls.

But it's better to have the pump below the water line anyway. This has three big advantages. The pump would be self-priming. The earth will help block the sound of the pump. And as koikeepr said, the pump will be more efficient with positive suction head instead of negative suction head.

 

[twinclouds]

Thank you both.
For in ground installation, my main worry is how to prevent the water reach the pump. I guess I can use a irrigation box to block the water to reach the pump from soil around, but what about the rain into the box? Thanks again in advance.

 

[koikeepr]

Right, it can be done with the pump above water line, you would then need a check valve in the pond below water line on your intake. Folks do it, but it isn't the most efficient use of an external pump.

I don't like to worry about air bubbles in the pipe too.

 

[Otter]

Thank you both.
For in ground installation, my main worry is how to prevent the water reach the pump. I guess I can use a irrigation box to block the water to reach the pump from soil around, but what about the rain into the box? Thanks again in advance.

Can you run a drain from the pump box to a lower point on your property?

You could use bulkhead fittings to make the box watertight even where the pipes come in. That and a lid should keep the rain out. The box might float up when it rains, though, so you'd want some concrete around it or in the bottom.

Worst case, you could put a sump pump in there with your pond pump.

 

[twinclouds]

Thanks. All these are good suggestions but all have some pitfalls. I will need to think about that. In any case, thanks for your suggestions.
I just wish they will have a submersible pump as efficient as the external pumps.

 

[Otter]

Check out Laguna's Maxflo series. These are low-head pumps, and the biggest one only pushes 4200 gph (more like 3200 in a typical pond setup), but it only uses 160w. I'm not sure if their specs can be believed, but I recently bought one, and once I get some plumbing done, I'll test it.

 

[twinclouds]

I would like to find one deliver around 4000 gpm in my set up and consumes less than 300w. This one is probably a little small but please let me know your findings.

 

[koikeepr]

It's a good suggestion, Otter. I had a Laguna that I used for many years without dilemma. They are good pumps and wattage consumption is low. I always recommend a Laguna if someone wants a submersible.