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Flood table medium choice

Posted by Astaroth none (My Page) on
Sun, Mar 2, 14 at 9:39

Hi there!
I have set up a 4'x3' flood and drain table in my basement, to grow lettuce, spinach and Swiss Chard.
I have the tables setup with a cover plate over the table that has 14 holes cut into it to hold 14 4.5 inch pots. There is a 6 tube T8 6500 florescent fixture for lighting.
I have the "Dutch Nutrient Formula" (DNF) two part liquid nutrient.

I'm trying to decide what to go with for medium. I have pee gravel and I have Coco coir (Peat). I'm leaning towards the gravel. I'd like to experiment and try both, to compare them head to head.
But that would be hard to do, the gravel would need more cycles flood cycles then the peat. The peat would need less nutrient then the gravel... So it looks like I need to pick one over the other. I have started the seeds in the 1.5 inch A OK rock-wool blocks. and will transfer them into the 4.5 inch pots.

If I do go with the gravel would 4 cycles be enough to keep the roots from drying out too much? It would make sense that pee gravel would hold less moisture then clay balls would. And I believe, if using the clay ball (Hydroton) the number of cycles in a day is 4. I currently have the pots full of pea gravel and the pump timer set to run every 3 hours for 8 minutes. The total cycle time for a fill and drain is 16.5 minutes. That's 8 minutes to fill and 8.5 to drain.

Any thoughts or suggestions would be greatly appreciated!


This post was edited by Astaroth on Sun, Mar 2, 14 at 21:48

Follow-Up Postings:

RE: Flood table medium choice

Those two would have dramatic differences in water retention. For your layout I would recommend lava rock bought at the local hardware store.
Holds water really well, isn't too heavy, and your system doesn't require smaller pieces. Unless you're in a particularly hot arid region, you'd likely only need to water them once or twice a day.

RE: Flood table medium choice

Thanks Grizzman,
The table is inside in the basement, so should not get hotter then 75-80 in the summer.

RE: Flood table medium choice

I have a flood and drain with both, why you ask? Best of both worlds. I use it for a nursery to get plants started to go into my nft system. On bottom of the tote is coco choir, on top is a 1 ish inch thick layer of pea gravel. I sit the seedlings in rock wool 98 at a time on top of the pea gravel. Flood 2x daily 6a 6p when the roots start into the pea gravel they are easy to pull out. The choir stays wet and keeps the pea gravel damp longer. Once I have a half inch of root out we pull the rockwool starts then they go right into the nft cups and into the rails.

Initially I tried choir only but the roots grew into it and couldn't be separated because the roots were damaged. The pea gravel alone seemed to dry quickly. I like it this way. We are making one 3x bigger to take care of our larger capacity this year.

RE: Flood table medium choice

@ Rio_Grande
Hey thanks for the input! Sounds like you have it pretty much figured out! I like the idea of having both. The gravel would help to keep the algae off of the peat. The gravel if / when it does get algae on it can be re-cleaned and sterilized.


RE: Flood table medium choice

Thanks, but I will never have it figured out! Lol it's too much fun playing!

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