Instructables

Sawdust as a medium for hydroponics?

Actually I have 2 questions pertaining to hydroponics. First you should know that I have a passive hydroponic system functioning right now the container is partially submerged in a nutrient solution with holes in the bottom of the container. The medium I'm using right now is perlite to allow more oxygen and act like a wick. I do have a top layer of aquarium gravel to anchor the plant better. I've been thinking of trying to add more oxygen to the roots by using an air pump. I was going to insert the tube from the top (the dry section above the water) pointing down to the wet section to blow some air to the roots. Would this be an unnecessary addition if I continue to use perlite as a medium?

My second question is the title, would sawdust work as a medium for hydroponics? I assume it would be able to act like a wick for a passive system my concern is would the roots get enough oxygen in sawdust? Also most mediums are inert sawdust wouldn't be, would that have a negative impact on my plant?


canucksgirl2 years ago
Regarding your first question. Yes, you need to add oxygen, as the plants are absorbing it rather quickly. If the oxygen content of the water is low, it will slow the plant growth.

Sawdust can be used, but it should be from a known source. You don't want saw dust that contains paint, varnish or any other chemicals.

Here's a link to a Hydroponics Website that contains some good information for you. The page I'm linking you to discusses the types of mediums you can use. From the menu, I'd recommend the Articles. There is a lot of information there that you might find useful, particularly the one on oxygen
thecoonskin (author)  canucksgirl2 years ago
thanks, sounds like I should go ahead with my oxygen plan then. Could I use an electrolysis apparatus to increase the oxygen level in my solution? I was thinking of having a 5 gal bucket filled with water and an added electrolyte (no salt so I avoid creating Chlorine) so I can create an oxygen gas and route the gas to my hydroponics tank thus increasing the levels of oxygen in the water. The question is what acid or base could I use for the electrolyte that won't create harmful byproducts? Do you think I should pursue the electrolysis plan or go with my original idea?
You dont need electrolysis to increase the oxygen in the water. Either use a small air pump to bumble air in the water (you can use something like an aquarium disperser to get smaller bubbles) or let the water "crash" into itself (like a waterfall or when you fill a bucket from a tap). This kind of contact between water and air should provide ample oxygen in your water.
I would stick to the original idea (only because I'm not sure how you'd work the other idea).
Oh btw, check your Inbox.
thecoonskin (author)  canucksgirl2 years ago
Just checked the inbox no new messages. Were you trying to send me something? If so it didn't go through.
Yes. I sent you a PM to your Instructables Inbox a while ago now (regarding your other account). It's not urgent but you might want to check it again later.
thecoonskin (author)  canucksgirl2 years ago
I logged out and logged back in to see if it would show up, still no message. Refreshing didn't help either. Did you send it to my other account?
I sent it to your thecoonskin account, and you shouldn't have to log out. (Honestly I'm not sure why you didn't get it). You should only have to click on "Inbox" (top right of website next to "YOU") to view your PM's (Private Messages).

Here's a screenshot of my sent folder. (Anything in orange is un-read).

PM.jpg
I just replied to your message (just so you know).
I don't think its you (or me) with the problem... I just sent an email to staff. I've got several PM's sitting in my sent box that are unread.
thecoonskin (author)  canucksgirl2 years ago
yea theres something wrong on their end because My inbox still has zero next to it IDK why it refuses to send me your message. Is it possible you could just post it here or on the comments section on my profile?
Re-design2 years ago
I would not use sawdust. As you now most mediums are inert. Sawdust will decompose and suck the nitrogen out of the water depriving your plans of it. Sawdust may cause mold to grow.
Mold and fungi in hydro are killers for the plants. We always use a media-less NFT system, with lots of oxgenating surface. We start the plants in rockwool and then put them into the troughs.
thecoonskin (author)  Re-design2 years ago
Ah I see I'll be sure to steer clear of it then.