Sand

[Harold Sukhbir]

A while back someone suggested sand as media being superior to gravel.After some searching i came across this article on lettuce grown in sand vs gravel with very interesting results. Traditionally i think sand was used early on in AP but was found to have problems associated with it's use (water retention,anaerobic problems,associated hardware problems etc.) Does anyone use this media and if so can you share your experience with it?

Here's the article...

mediaandfiltrationexperiment.pdf

[Rick Op]

Harold Sukhbir said:
   lettuce alone

Off-Topic...  I got an unexpected smile from this, remembering my late father-in-law.
He joked that "lettuce alone" is known as "Honeymoon Salad"

[Harold Sukhbir]

Hey Rick I'll keep that in mind for when I'm gettin married!

Rick Op said:

Harold Sukhbir said:
   lettuce alone

Off-Topic...  I got an unexpected smile from this, remembering my late father-in-law.
He joked that "lettuce alone" is known as "Honeymoon Salad"

[Brian Naess]

Many of you may not be aware, but the folks at NC State who basically invented what we now called aquaponics used sand as their growing media with great success. Here's an article that summarizes some of the experiments of Dr. Mark McMurtry.

 

I've always used gravel/hydroton, but I recently built a 100 gallon system that is using sand. I'm cycling it right now, but am preparing in the next week to stick some seedlings in it to see how things go. I was using one of the aquaponic spider valves, but I'm not happy with its performance, so I've ordered a small aerator for the fish tank and will reconfigure the fish tank pump and plumbing to remove the spider valve after it arrives. I'll be able to use a much smaller pump.

 

The benefits that I've seen so far:

- You really don't need as much flow

- You don't need to cycle the water through as often, since the sand does a better job of removing the nutrients

- Sand is cheap.

 

I use a separate water catching tank and fiberglass window screen to keep sand from getting into the fish tank, and it seems to be working pretty well so far.

 

Like I said, though, my own experiment is still in the early stages - without plants. I do have two large goldfish in the fish tank right now, and the water is clear and happy. I am convinced that the sand does a better job of removing nutrients.

 

Dr. McMurtry said that there will be an algal mat build up in the early stages of growing, but he said that this mat will actually play a vital role in nutrient removal. I'm starting to see that mat develop.

 

I'll post photos to my blog and update this thread when I've got the aerator installed.

[Harold Sukhbir]

Hi Brian,

Great idea using a secondary catchment vessel with screen. Are you using any pre-filtration from the FT to GB? Nice article by the good Doctor who helped AP to evolve to what it is today.

[Brian Naess]

No, I'm sending the FT water straight in. I slow it up a little. Here's my blog entry on my system. I'll update the blog after I take the spider valve out of the mix. Note that the article mentions explicitly to NOT pre-filter the water going into the grow beds, as that removes key nutrients and your plants will not be happy.

[Harold Sukhbir]

Sorry Brian i read that article sometime ago and yes it does mention no pre. I like you blog page showing pics of your neat system. I love the neat DIY construction design!