All About the span of time to water the grow bed

[Ma. Theresa Macapil]

hi there, I just want to know if it would be possible to switch on my pump for half day to distribute water to my grow bed? you see, electricity bill is way up high here in our place. Is putting it off once in awhile wise enough?

[TCLynx]

There are a few considerations to take into account when figuring out how long you can leave the pump off.

First, you need to make sure you have enough filtration and aeration to keep the water quality good for your fish.  If you pump too little, your fish may suffer.  So you want to keep a close eye on the water quality and your fish to make sure you don't go too far.  During warmer weather or with heavy fish loads you will probably need to pump more and I would definitely recommend some supplemental aeration if you are going to leave your pump off for extended periods of time and this will probably reduce the amount of savings you see by leaving the water pump off longer. 

As you extend the length of the off time, you may want to test the ammonia from the fish tank right before you turn on the pump again to see if it's starting to rise.  If you see a rise in ammonia before starting the pump, then you have probably extended the off time just a bit too long and you should shorten just a little.

Next, the plants may be fine with extended periods without the beds flooding.  How long will depend on how hot and dry it is and how greedy the plants are.  During hot afternoons the plants will probably need more water but you might only need to flood once overnight.

[Ma. Theresa Macapil]

Thank you for your reply, there is much I need to know more about aquaponics before setting up one in my backyard.

[TCLynx]

One key to dealing with high energy costs is to research energy efficient pumps carefully, often times spending extra on a good pump in the first place will save you far more than the difference in price to the cheap pump in the first year of operation.

Another is to carefully plan heights and pipe sizes to maximize pump efficiency.

[Chris Carr]

Do you have any rough guidelines on this which you would suggest from your experience? You seem to have it mastered with your old system anyway. I assume minimize lift and maximize use of gravitational potential are a given. I think minimizing pipe size without causing unneeded resistance when possible makes sense, or does it?

TCLynx said:

Another is to carefully plan heights and pipe sizes to maximize pump efficiency.

[TCLynx]

Yes the careful balance of making sure you have enough fall for your drain time while still minimizing lift yet keeping everything at comfortable heights.  This will be trickier with siphons than with timed flood and drain or constant flow/flood.  With siphons you are best off with at least several inches of fall below the grow beds to make balancing the siphons much easier while a timed flood and drain can have the drain line empty to no lower than the bottom of the grow bed and still work, heck if it actually has to drain above the bottom of the grow bed a bit, that only means the bottom of the grow bed will never completely drain but if you have deep grow beds that isn't a big deal.  Constant flow/flood you can have things almost all at the same height with only small variations but you loose the benefit of having falling water help aerate for you so you need supplemental aeration instead.  Constant flood of some sort or a raft system may be the best choice for ultra low energy low density operation.

Always go bigger on pipe size, spend a bit extra now on the bigger pipes to save money on electricity.  I've found with smaller pumps I can usually up the pipe size quite a bit from the pump to gain better flow rates.  For instance, From my little 50 watt quite one 4000 pump which has a 1" plumbing fitting, I upsize right away to 1 1/2 inch going to an indexing valve.  That little pump can operate a gravity modified indexing valve as long as the valve is only about 18 inches above the water level in the fish tank and the surface of the grow beds is only about 18 inches above that, but If you came off the pump with only 1" pipe, I don't think it would manage nearly so much.  I definitely know that the Danner MD18 pumps benefit from increase of pipe size.  Those pumps come equipped with only a 3/4" fitting!  Now those are strong little pumps  and definitely deserve bigger plumbing or you will lose an immense amount of flow to friction.  1 1/2" pipe is what I usually connect that pump to and I only go smaller once the plumbing has reached maximum lift and I branch out to say feed 40 towers where I might be using 1" pipe from the main branches and go down to 1/2" to actually feed the towers.  By the way, that Danner MD 18 can operate the Regular aquaponics Low flow indexing valves of any size but I would still run 1 1/2" pipe from the pump to the valve and may even T off for a bypass before the valve in case I need to reduce the flow through the valve.  I am also becoming fond of the automated valves (like they use for swimming pools and stuff) to alternate flow between indexing valves and something else because I was having to replace impellers too often when turning the pumps on/off all the time.  The automated valve means I can operate twice the amount of stuff on the same amount of pumping power, it just means everything gets intermittent flow but I've found that to be a good thing.  The pump never stops which is generally better for the pump and it is a constant draw on power rather than spiking every time it turns on.

[Chris Carr]

 

All great information. It is much appreciated.
 
TCLynx said:

...