Water use actually 10%

Posted by Dr. George B. Brooks, Jr. on April 30, 2012 at 11:00pm

It really is quite remarkable. When I first read the literature that stated that aquaponics used about 10% of the water of a "regular" garden I did not believe it or at least there is no way for that to be possible in Arizona. So I tested the hypothesis. At this time of year or with this level of heat a "normal" garden on drip uses about 1 gallon of water per Ft2 per day. As of today I am using 0.08 gallons per day or just under that 10% number. This has got to increase as the weather gets warmer and plants grow larger, but results so far suggest the short and long term water savings potential is still quite astounding.

Photo: http://bit.ly/IikmJx

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Replies

  • Dr. George B. Brooks, Jr. August 23, 2012 at 8:43am

    Just passed the 40 lbs of harvest mark for this year. Not what I had hoped but all good things in time.

  • Caroline August 15, 2012 at 10:30am
    That is what I'd heard. It is so wonderful to see the data.
  • Nick Mayes May 31, 2012 at 6:15pm
    Looks very nice! With my aquaponics setup I am using a combination of nft and flood and drain. Instead of using a small trickle of water constant on the root system in the tubes I have my canister filter set at 75% and I flood the entire tubes with water and let it drain out with gravity. I have the filter set on timer at 15 minutes on and 15 off. In the heat of the day I have it set on 30 minutes on 15 off. I have found that giving them the 15 minutes off seems to stimulate the root growth making for a bigger root mass. What kind of fish to water ratio are you using? What kind of temperatures are you seeing in your reservoir? I look forward to seeing the progress of your setup! Excellent job! Just a side note. You should try a couple of humming bird feeders over the reservoir the waste will benefit the system a great deal. Worked great on my system.
    • Dr. George B. Brooks, Jr. > Nick Mayes June 4, 2012 at 5:08pm

      I forgot. Current water temperature 78oF

    • Nick Mayes > Dr. George B. Brooks, Jr. June 5, 2012 at 2:47pm
      I have trouble keeping mine at a constant temperature. I know lettuces like having water temps in the 70s any method you have of keeping your temps in the 70s?
    • Dr. George B. Brooks, Jr. > Nick Mayes June 7, 2012 at 7:43pm

      1,200 gallons of water is a great heat sink and does not change temperature quickly. This in combination with cool nights, the water being shaded by plant growth and low humidity keeps my temperature stable for the moment. This will change however in August when summer hits its peak. We shall see what happens then.

    • Dr. George B. Brooks, Jr. > Nick Mayes June 2, 2012 at 4:37pm

      Greetings. RE: Fish/Water ratio. I do it a little different. Dr. Rakocy's work suggests that approximately 1m2 of grow bed is needed to convert the ammonia generated from feeding your fish (in this case tilapia) 100 grams of feed per day into nitrate. If you are feeding your fish a growth ration of 3%/day then your maximum carrying capacity would be about 3.3 kg (7.26 lbs) per m2 (about 10 ft2). My grow bed area is about 5m2 so I should be able to carry about 36 or so lbs at any one time. This density is relatively low risk and could probably be pushed if one is more adventurous. 

  • Dr. George B. Brooks, Jr. May 13, 2012 at 4:05pm

    Ok, now a am really amazed. Despite doubling the aeration, much warmer temperatures and rapidly maturing plants thus increasing evapotranspiration, the water use between today May 13th and April 30th increased by only about 34% to 0.107 gal/ft2/day. To quote my favorite fictional character "fascinating." 

    • Dr. George B. Brooks, Jr. > Dr. George B. Brooks, Jr. May 19, 2012 at 9:47am

      As expected increasing temperatures, wind, low humidity and increasing plant maturity are increasing water use. It is now up to 0.21 gallons per ft2/day, an increase of 94%. I must now determine what the water usage is for drip systems under the same weather conditions to see how close to that 10% water use number we still are.  It will be interesting to get a years worth of data.

    • Dr. George B. Brooks, Jr. > Dr. George B. Brooks, Jr. May 26, 2012 at 7:46pm

      Only a small increase in water use this week. Now up to 0.23gpd/ft2. An increase of 10% well within the margin of error for saying no increase at all.

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