Waterfall off main pool pump help

[Azecco]

I have a new 27' (50" deep) above ground pool in which I built a stone waterfall to the edge of it that is 4 ' wide and the plumbing going to it is about 7' to the left and 7 ' above the main pump that the installers installed it at. The pump is a Hayward 1.5hp pump with a 3hp rated doughboy sand filter (it's big). The flow of the pump is very strong and pushes two jets into the pool. When I turn off one jet and turn on waterfall there just isn't enough pressure or consistent pressure to keep the water fall pushing strong. It sometimes has enough pressure to push the water away from the wall and looks great, then it losses pressure over 30 mins and is dribbling down the wall. Or many times it just dribbles down the wall.
I want it to be a solid sheet of water coming out all the time. Do I need a bigger pump? Or do I add a pump for just the waterfall? And if I add a pump, does it draw off the same water inlet that the main pump is drawing off of?
(Please excuse my lack of correct industry terminology, newby here)

Side note: when I first starting to use it, I had to backwash my filter for a minute or two then the pressure was enough to turn on water fall (after placing the filter back into filter mode) to last for an hour or two before the waterfall lost pressure.

 

[Richard320]

Welcome!

There are two possibilities for low flow.
1) The filter is clogging
2) You're drawing air in and losing prime.

If the pressure is high and goes down after backwashing when everything is working right, the filter is clogging. That's probably a chemistry issue - an algae bloom.

If pressure starts normal and goes down as the flow decreases, you'll probably also see air in the pump strainer basket. That can be as simple as low water level or a sticking skimmer flap.

So, to help diagnose
What does the water look like?
What are your test results?
What is the normal filter pressure when things are working right?
What is the filter pressure when things slow down?

 

[Azecco]

Thanks for your reply. I don't have a gauge on my pump or filter, how do I go about finding the pressure amount? The pool is a round 27' that is very clear and clean. All levels are checking out perfect (according the Clorox test kit and their phone app) on chemicals and the water pressure looks very strong moving the water very well.

 

[Richard320]

I'd check that filter closely for a missing gauge and a pipe plug where it belongs. And then install a gauge. Even the cheapest tiny intex sand filters have a gauge.

You're not reporting air in the basket and the water is pristine so I'm out of ideas.

 

[pooldv]

What is the flow like out of the still open pool return (jet)? What if you close off or block it?

 

[Azecco]

Pretty strong flow when it's closed. Is the distance of piping the cause maybe? Need a bigger pump? Or do I add a pump for waterfall only? I've been told this pump should work but don't know.