ᐅ Cistern pump, are price differences justified, any experiences?

Gardena does not offer suitable pumps. Those are domestic water systems… Pumps come in all varieties. As mentioned, a deep well pump is the recommended choice for price/performance. We have different requirements and therefore use different pumps (Wilo). Those units cost several thousand euros each. Graf also has a combination pump with level monitoring, refill function, etc. But that one is already over 2,000 euros.

This is about a pump for a 5m³ (5,000 liters) rainwater tank... I think a 750 EUR pump is completely, absolutely over the top.
With all due respect, your 50m³ (50,000 liters) tank is not a valid reference at all...

A 5m³ (5,000 liters) tank is usually empty most of the time from spring to autumn anyway... so the pump hardly runs at all during that period.

The very inexpensive pumps like Gardena and similar brands only generate low pressure. @rick2018 is right, you just need to look at the pump’s performance curve. With a maximum pressure of one bar, only a small amount of water comes out of a long hose, so using sprinklers is out of the question. In my opinion, pressure becomes acceptable starting from 3 bar, but it depends on the height difference, which you need to calculate from the pump in the cistern. Ten meters (33 feet) equals one bar. In our case, the pump hangs about 5 meters (16 feet) deep in the cistern, so the first half bar is already lost by the time the water reaches the tap. I consider pressure to be more important than flow rate, especially when dealing with a small cistern.

It is 76m2 (818ft2) 😉
But it’s not just about the size of the cistern. How many meters of elevation need to be overcome, what flow rate is required, and so on.

rick2018 schrieb:

It’s 76m² (818 ft²) 😉
But the size of the cistern isn’t the only factor. How many meters (feet) of vertical height need to be overcome, what flow rate is required, and so on.

I’ve done some more research now. Apparently, there is a newer model, the NiRo 40. My requirements are relatively straightforward. The garden to be watered is about 130m² (1,400 ft²), of which around 70m² (750 ft²) is pure lawn, and the rest consists of flower beds, shrubs, and so on. The plot is almost square with no height differences, the cistern goes down to about 1.5m (5 feet) deep, and it is a shallow tank.

The NiRo 40 has the following specifications:
- Rated power: 1.0 kW
- Maximum head: 40 m (131 feet)
- Operating pressure: 4.5 bar (65 psi)
- Maximum flow rate: 5700 l/h (1505 US gallons/hour)
- Maximum immersion depth: 5 m (16 feet)
- Maximum suction height: 8 m (26 feet)
- Maximum suction length: 12 m (39 feet)

That should be more than sufficient when I compare it to your comments here, for example regarding operating pressure. Right?

Thanks to you all!

Yes, that would work. For the controller, I recommend Hunter Hydrawise. The smaller model with 6 zones will be enough for you. Please choose sprinklers and other components from Hunter, Rain Bird, Perrot, etc., not Gardena. Professional components are more durable and usually more cost-effective.