There are different technologies for different max heads. Some pumps are designed to move more water at higher heads than pumps designed to move more water at lower heads. And everything inbetween. You'd have to check the specs for each pump. I'd assume these two pumps would be basically the same as far as max head, but don't know off hand.

The second thing to check is pipe size. I don't know off hand the flow rate of each pump at 5' head, but just using the max gph there is a big difference in friction loss for 1.5" PVC, I don't know about the flex hose. With 2" PVC the loss is very close for both max gph. What this means is the 4200 pump is probably being restricted even more than the 3500 was.

The third thing would be how many watts these pumps use at the 5' head. The 160W and 250W numbers I assume are the max watts the pumps use. That would allow you to compare the two pumps for your specific application. Finding power use charts can be difficult unfortunately.

I think then you could evaluate whether the new pump was working correctly.

Thanks for the reply.
My pipe in 4" PVC for most of the run (about 11-13 ft). Both pumps have 1 1/2" outlet, so I'm limited there,as is the input to the filter at 2". The 1.5" flex hose is only used from the pump to the edge of the pond (about 3') then the 4" PVC the rest of the way, till it hits the reducer to get into the 2" opening of the filter. I used the 4" PVC exactly for the reasons you mentioned, however I cannot change the output of the pump or input of the filter, so I have to live with those limitations.

Also, with the pumps in shallow 1' of water all by themselves, the Beckett seems to have more oomphf. 'Tis odd.

hi yota. I suggest you snoop about for a "pump curve" for your pumps. This should further help you understand the differences and capabilities of the two pumps. The curves will likely be similar but give you an idea of what to expect based on plumbing restriction (head or pressure).

These curves often show flow versus head versus power. So you should get good idea of power required in a given application (flow & head/pressure).

Hi Yoda,

I would guess that by looking at the wattage of both pumps that you are looking at two different drives on these pumps. I would guess that the beckett is a direct drive and the Laguna is a mag drive. Direct drive pumps usually can pump more water at higher head heights. If you wanting to get more flow from the Laguna pump you will want to at least 2" pipe right at the pump. That length of 1.5 pipe is adding a lot head height to the system.

Mike

yoda, sorry, I miss read 3 ft to 4" PVC.

In the "Are 2 1200 gph pumps the same as 1 2400 gph?" thread it was explained and shown to me by Mike that the data provided by manufacturers should not be trusted to be be very accurate. I think going forward I'm going to trust it less, maybe not even consider it at all beyond max watt for circuit loading.

Waterbug guy,

It was not my intention to have you not trusting pump manufacturers. What I do is this. If what a manufacturer says is too good to be true I suspect that it is not true. I use pumps from manufacturers that I know are understating what their pumps can do. That I know I will get what I am looking for.
Mike

Mike,

You pointed it out to me, but it wasn't you who convinced me to not trust manufacturer data, it was the data. In addition to the Sequence mistake I saw one in the Danner data too. That was a pretty small survey and I didn't look that close at the remaining material. So, yeah, looked pretty untrustworthy to me. I don't think manufacturers are doing this intentionally, just lack of caring on their part and also on the part of customers. Apparently few people are checking the data or care enough to complain. Most manufacturers don't even bother to provide any data and that sure doesn't seem to hurt sales.

Seems like most people just go by the max watts and call it a day.

If I had a way of knowing a manufacturer was understating or accurately stating performance I'd go with them too. And the way you figure which are and which aren't? Can only be from experience of using lots of pumps from lots of manufacturers and performing exact tests yourself on each, keeping careful records and then hope they don't change something the next time you buy a pump. Listen to some opinions online? I haven't been that impressed with opinions over the course of my life no matter the source so I have to pass on that.

For me it can't really be both ways. Manufacturer data can't be suspect and also be used to make decisions. I'd feel like I'd be kidding myself. That's just me.

I think I'll just go with the crowd and use the max watt and GPH too. Maybe at some point I'll test pumps myself and return pumps that don't perform as expected.

Thomba,
Interestingly enough the Laguna is rated higher at ~ 5.5 ft of head also:
Beckett 3500 2875 at 5 ft.
Laguna 4200 2853 at 6 ft.

Now the Laguna is 22 GPH shy of the Beckett, but it's rated 1 ft higher (6ft opposed to 5 ft) Like I mentioned, I'd definitely give the edge to the Laguna there.....at least on paper.

As I mentioned on a prev. post, even if you put the two side by side in about 1ft of water in the pond, disconnected to any piping, and just plug them both in and let them rip. There is certainly a difference between the two. The (smaller) Becket has much more "thrust" and a more violent water display. I can only assume that this translates into more GPH.

Waterbug,
I think I'd have to agree with your last post. Max watts are watts. To loosely compare with an automotive engine, there is no substitute for raw C.I.D. Looks like with pumps, "highly efficient" designs are no substitute for pure running wattage.

At only 800 RATED watts over the Laguna 4200, it'd be pretty impressive to see the Beckett 5000 GPH (same family as the 3500) in action, since the 3500 is RATED 700 watts BELOW the Laguna 4200 max-flo, and it appears to be a much more powerful pump in it's own right.

Thanks to everyone for the wonderful input on this. Esp the point made about the mag drive vs direct drive. I'm not certain on the design of either, did a little research and was unable to verify either.

yota, I wouldn't translate more "thrust" into being more GPH. More pressure maybe, and that would translate into probably less GPH when comparing apple to apples. Only way to know GPH is with a 5 gal bucket and a stop watch imo.