Episode-2716- Round Table Topics for 8-20-20 — 15 Comments

  1. I really enjoyed this show.  I would love to hear you talk more about M3…..maybe an idea for a future show.  Thanks!!



  2. Jack, are you going to flood and drain with the VM due to algae/mold issues?

    Brain has been working on how to make it work since listening yesterday.

    V.1 – Float valve that works the opposite of toilet float (closes valve until full, then opens valve)

    V.2 – Sprinkler valves on timers. Use valve on drain pipe. Drain into ‘next’ tray. Really these are only on the deep trays. So pump the water into the top and let drain into the 1st deep tray (same as now). Let it sit for x minutes. Drain into next tray, repeat. This version takes 2 valves & timers (pricey). Was thinking you could do one valve connected to both deep tray drain valves, but this has the same problem as the current system…too much draw down on the reservoir.

    Which made my brain go to…

    V.3 Just get a bigger reservoir =)

    If you’re stuck with a ‘small’ reservoir, I think you’d call this ‘new’ type of system ‘sequential flood and drain’. Would be very easy with a microcontroller & some valves, but I’d prefer something simpler if possible (brain still working on it).

    Looking forward to seeing what you come up with.

    Working on my own v.2 system with LESS greens (can’t eat them all) and LESS microgreens (ditto. really can’t fill up that shallow tray, need less than half that much space) but with some added tall trellised plants (cucumbers and tomatoes. cucumbers grew fine in the bottom deep tray, trellised up the back of the regular VF but will choke everything else out if you don’t manage them).

    2″ pots got pretty choked with stalks/roots so I get going to 4″. When the plants get big they tend to topple or pull out the 2″ pots (IME).

    • @insidious the easy answer is of course a bigger reservoir, but then you don’t have a system easy to relocate.

      The 40 gallon commander is about the biggest thing off the shelf that will fit in the bottom space of a 4×2 rack system.  With castors you can move it as a self contained system.

      Algae is not the problem, flood and drain can make it worse, the algae I got before was all in the top tray (flood and drain) but F/D just grows plants better.  My method, two bulkheads and one with a stand up and drain back though the pump like works fantastically.

      I think simply holding some in the deep trays will solve the issue, right up to the top of the dead space, then I only need raise the level 2 vs. about 4.5 inches.  I could even hold a half inch on the net cups and be fine.  By simply distributing some of the fluid to stay above the issue should be solved and weekly top ups should be all I need.

      Ill need to add chloroplast sheets to those trays so the fluid is not wide open to light that is where the algae becomes a problem.  This happens in my top tray as I run it open.  About every three weeks I pop it out, spray it with bleech, let it bake in the sun for ten minutes and rinse it out.  Pop it back in, done.

      The freedom to throw anything in it and do starts, micros, you name it make it worth doing but I’d not want to do it with the lower deep trays.  Had I known what I know now I may have done all shallow trays.

      • Let me add the new version is supposed to be run fully by my grandson and wife so it needs to be dead simple.  Otherwise their “help” will end up making it just more not less work for me.

  3. Thinking in comments… =)

    The sprinkler valve idea was to use it on the ‘drain’ pipe (not saying this will work for you). System same as v.1 except add ‘drain’ to both deep trays. Drain line to res, with sprinkler valve at end of pipe. Valve is closed during cycle. Opens between cycles to drain trays. (still doesn’t work for 40 gallon reservoir).

    With ‘sequential flood & drain’ (more complex!)  you still need 20 gallons to flood + 4″ for pump + 5 gallon draw down. If you stick with the 40 gallon container, that’s still 34 gallons of water (283 lbs). A smaller footprint tub would lower the amount of water needed to keep the pump under water (with this tote 9.2 gallons, or 77 lbs of weight are because the pump isn’t in a sump).


    For those thinking about this, roughly 4.4 gallons per inch of water in the deep trays.

    2 trays x 4.5″ water = 39.6 gallons

    + maybe 1″ for shallow tray = 4.4 gallons

    So your 40 gallon reservoir is going to be mighty empty (it’s a wee bit less as the trays taper).

    40 gallon commander tote is 17″ deep, so about 2.3 gallon per inch. Pump is about 4″ tall (9.4 gallons). Transpiration loss per week for me is about 5 gallons.

    Math suggests I can raise the water height during the cycles in the deep trays 3″ max


    On Weight:

    v1 VF – 17 gallon reservoir + 39.6 gallons in deep trays (472 lbs.)

    v2 VF – 40 gallon reservoir + 22 gallons in deep trays (if 2.5″ water held in trays) (517 lbs.)

    More weight at the bottom for moving though.

    • I may be misunderstanding here though, because you may be lowering the net cups & the flood level so that total flood depth (2.5″ held + 2″ flood) is LESS than 4.5″.

      • So 4 inch cups sit on the bottom of the tray but as you know they have sort of a false bottom grid and it takes quite a bit of water to fill that before the part the cups are in begins to fill.  If you hold all of that full (based on the height of the delivery pipe) none of that water need be in the bottom tank.

        Now a 4 inch cup is also 4 inches high base to rim but to grow the type of stuff we are doing here that isn’t all needed.  The part of the cup with openings is 3 inches high base to tip.  LECA is also very wicking in nature.  The Rapid rooter plugs are also about 1.5 inches long.  If you fill the cup to the top of the holes with LECA, when you pop in the plug the bottom is now only 1.5 inches from the bottom.  See where this goes?

        If we now hold .5 inches above the false bottom in the top tray, even raising 1.5 inches in a cycle puts the plug itself .5 inches (a full third of its length) under water.  Fluid is now coming about 1 inch shy of the top of the LECA which is PERFECT for E/F.

        You are now only asking for a total of 3 inches in rise and fall across the two lower trays.  In the flow though model you were already doing about 1 inch, so you are asking only for two more.  And the end of a cycle the LECA will be hydrated almost to the top, it can easily go 45 minutes or even 90 until the next cycle.  By keeping .5 inches in the fluid it will never fully dry out anyway.  Yet you get tons of air exchange.

        Should this not make a week between top offs possible I have a silver bullet.

        Two pumps, two timers, one runs the shallow tray and one deep tray, one runs the other deep tray.  I don’t expect this to be needed but if you want self contained it is the easy button.

        • With two pumps could split the reservoir into two bins (reuse the one from v1). Would allow more water if needed, and allow different nutrients/depths/water change times.

          Seems like the single giant reservoir walls might bulge more (don’t know that they change the wall thickness based on bin size).

      • I hate the two tank idea, right back to capacity issues and more topping up.   The 40 gal commander filled an inch from the top didn’t seem to have any issues.  One thing you could do if worried, use fender washers and all thread to reinforce the top.  I have thought about this for long term stability.  Two pieces at the top, about 1/4th in from the ends across the shorter axis would make it pretty bullet proof you just want BIG fender washers.

        • That said two tanks with a bulkhead connection would effectively give you greater capacity with less issue.  One more point of failure though.


  4. Or…could create a ‘faux’ sump by taking up space around pump at bottom of 40 gallon container. 2″ Styrofoam x2 with a rectangle cut out for the pump. Hold it down mechanically or glue it. Would reduce water weight by 70-75 lbs & get total water weight to around 210 lbs. =)

    I may actually do this in my current reservoir, as any liquid volume below the pump isn’t getting me anything except extra system weight.

  5. @ another VF idea…

    pump water like current system (into top tray)

    overflow drains into middle tray. add drain/return line, but put a cap on it with a 1/4″ hole in it. overflow remains the same.

    same on bottom tray.

    so pump/flow is higher/faster than can be drained out of the 1/4″ drain/return line, but after the pump stops the trays will drain completely.

    In theory, you could just use the existing overflow pipe, but drill a hole in it at the base, particularly if you’re going to leave some of the water in the tray (0.5″). This would save some bulkheads and piping.

    =) – still mulling this over