Backyard Aquaponics
A place to discuss aquaponics

I was heading down the bell siphon idea but now Im considering the timed f&d. 2 questions pop in my head.

1. In us where and which timer to get. To me timers have specific times and the whole 15 on 45 off concept seems odd to me. Are these hydroponic specific timers?

2. Someone mentioned you may need a pump 4 times bigger on a timed setup because you only have 15 mins to move the water in the system instead of 1 hour. Any truth to this?

Pershing

It's recommended you turn over your entire fish tank water volume, through your grow beds, at least once per hour to achieve sufficient bio-filtration. If your pump is only running for 15 mins every hour then it has to pump the entire fish tank volume through the GB in that 15 mins... so has to pump 4x more water than a pump in a similar sized system running an auto siphon where the pump runs 24/7

Even if decide not to turn over the entire fish tank volume every hour, that's up to you, but either way the pump in the timed system would still need to be 4x the size of that in the siphoned system to turn over the same volume every hour... because it's only running for a quarter of the time.

Well that makes things interesting cause now the initial cost of the pump and timer need to be put into the equation. Seems the larger the pump the price spikes exponentially. In sure the usage also will go up possibly x4 which if it is the case then you really would not see a whole lot of savings? Thoughts forum?

As pumps get larger the wattage required to run them tends to increase at a greater rate than the actual output of the pump.

Quick example:

AquaPro AP 1050 pump uses 18w
AqauPro AP 3000 pump uses 75w

So the second pump has slightly less than 3x the flow of the first but uses over 4x the power.

I'm sure people will find different examples/brands that have different flow rates/wattages etc, these are just two sizes I regularly deal with and know the wattage of.

...in saying all that, only a few years ago most people didn't think twice about installing multiple 75w globes throughout their houses!

Figured as much, so you got the initial cost increase (bigger pump), plus the timer and plus the increase in operating cost. Im not seeing the benefits. Anyone with eeal world data to backup the costs benefits of timed F/D?

If you run on a 15/45 timer system then remember your power cost is a 1/4 , so a 80 w pump would only use 20 w for each cycle. Higher the wattage then normally the more head height it can pump as well.

Right, but because you need a pump x3 x4 times bigger your wattage usage might be the same or more. See example above. Dividing by 4 still the same wattage, actually a little more.

Power use varies between brands for the same amount of pumping, for example, my PondMax 8000l/hr (6400l/hr @ 1m head) uses 125W, so would use less kWh/day than the AP1050 listed above for the same volume of water moved... so the theory that larger pumps use proportionally more energy for the same amount of pumping aint necessarily so!

I'm thinking of using my PondMax as my backup pump and buying a Universal Pumps sump pump for my main pump, which will move 6100l/hr at 1m head, and consumes 100W.

At 1m head, that's 61l/hr/watt vs 51l/hr/watt for the PondMax.

I'm running 40m on/20m off through the day and 20on/40off at night, at the moment, although I do cut the run times back a bit in extended periods of cloudy weather so that I don't need to run a generator to charge the Lithium battery.

Another variable could be that you use a smaller pump and have it running continuously but shift the distribution of the water to different areas by using valves.

I am currently researching how this could be done.
Is there something called a "spider" that does this?

I saw a video from TCLynx in youtube that had an example of what you want. Im not sure if I spelled it right. It was like a spider looking thing that would open one at a time.

The aquaponics valve does this which Rupert and TCLynx sell.

Certainly is Happyfarmer...

But you still have to turn the pump off and on to change outlets of the valve...

Typically, yes... although the flow can be interrupted in a continuously pumped system by a flout or something similar...

To answer the OP's question about the timer, most home mechanical timers allow you to "program" them in 15 minute increments over a 24 hour period with little switches around a rotating dial. So you flip one on and the next three off and repeat 24 times.