NFT Setup question (hole size / slope)

[Nick Scud]

Greetings Forum - I'm in the middle of adding a bypass circuit to my sump return, and figured this would make a good excuse to build an NFT addition to function AS a bypass..

I currently run a 275 IBC fish tank and 2x 14" deep IBC grow beds via siphon.  Each bed has its own independent drain line (1" pvc) which returns to a 55 gal drum (burried) as a sump.  I retro-fitted a single 35 gal roughneck bin as a mini raft-bed, it's fed off the drain line of bed 2 (which also then returns to the sump). 

Inside the sump is a 1260gph pump, which pumps water back into the fish tank.  1260pgh is more than ample to feed a second circuit - I'll be splitting the sump-hose into 2 pieces:  1 goes straight back to fish tank, and the other (2nd feed) will trickle into an NFT "zig-zag" built of 4" PVC sections.  Each section is 62" long and there are 3 sections, so it's basically a zig-zag forming a "Z".  At the end of the zig-zag is a 1" uni-seal with a 1" pvc drain line going back into the sump.  I've posted a few pics so y'all could see what I'm talking about..

A few questions on the NFT portion:

1)  What are the best hole-sizes and spacing to drill??  (It seems like 3" holes, with 6-7" in between each)

2)  what are the best "cups" to use?  I've seen people like Omar using styrofoam "outer" cups with a slotted hydroponic grow cup inserted - is this the best method?  And again, what's the best hole-size to cut??  (you only get 1 shot with the hole saw.. can't adjust hole size once it's done, so better to ask now and cut later!)

3)  How important is the down-slope or pitch of the zig-zag?  I have mine basically moderatly pitched (maybe 3-5 degrees, max) - see pics.  I'm using 2x 4" PVC 90's to connect each leg of the zig zag - 4 total, 2 at each of the 2 unions). 

4)  Do I need to build a "baffle" or some kind of partial "block" inside each section of 4" pipe, to keep a certain basic level of water in each section, or do I just let it flow unrestricted?

I hope this is written clearly enough so it's understandable.  Please see the pics for better detail, and thanks in advance for your input and suggestions!!

kind regards

-nick scud

[Hydroponics Curacao]

Spacing depends on what you'll be growing. I used 10cm spacing and the holes were 5cm. This is my first time with NFT and it is doing amazing. The slope I chose is 10cm. The water shouldn't go too fast through but too slow isn't good either.

[Dan Lindey]

    I used 4" sch40 and bought 3" hydroponics pots and a 3" hole saw. I drilled my first 3" hole and the pot fell right through so I had to go back and buy a 2 7/8" hole saw. That drilled the right size hole and the pots fit perfect. As for slope I started out level so the bottoms of my pots all just touched the water then after the roots started to show I lowered one end by 1/2" and ajusted the water level so it just missed the bottom of the pot and only the roots are touching the water. This gives lots of air space for the roots to grow through before they hit the water. My only concern now is if the root growth will eventualy plug up the pipe.

     Warning: This is my first attempt at this and am in no way saying this is the way it should be done. I'm just telling you how I did it and it seems to be working nicely.

[Vlad Jovanovic]

My 2 cents...

1) "Best" size holes (and spacings) will depend on what you are growing. No need for 3" net pots for short term small crops like lettuce, basil etc...

2) I like to use/order net pots from these guys http://www.hydroponics.net/c/166 the 'grow-pro' pots all have a 1/8" lip...so if you order a 2" net pot you can use a 2" hole saw and not have the pot fall through (since the top of the net pots outside diameter is then 2-1/4" ). They are more durable than some of the other net pots I've used/bought...and they don't seem to come with as many quirky manufacturing fuck-ups (like poorly molded plastic on the bottom of the pots, or bottoms being practically solid with plastic instead of nice defined slits for the roots to grow through). 

They're pretty quick to process and deliver orders as well, which is always nice.

3) and 4)  The slope and flow rate can be pretty important. Although this may play out differently in the "homespun round PVC pipe" type of NFT rig that most folks here seem to like to use. Normally the NFT gulley's are flat bottomed and you really only would want a very thin film of water moving through at about 1 litre per minute. Dr. Coopers recommended slope of 1:100 seems pretty unrealistic for us 'normal' folks using crappy materials in less than perfect conditions/physical environments. But 1:50, 1:40 or even 1:30 is usually totally doable.

I imagine that in a round PVC pipe you'd have a much bigger volume of water in there, but would still not want the water to be whizzing on by the roots too quickly...(in classic flat bottomed NFT it has been reported that anything much beyond a flow rate of 2 litres per minute, seems to cause some deficiency issues...So play around a bit :)

Is that NFT rig in your pics fed directly from your fish tank with no pre-filtration? 

[Nick Scud]

Vlad - the NFT snake is fed from the SUMP - meaning the water has already drained through the grow-beds and is returned to the sump - the sump pump originally pumped water ONLY into the fishtank, however I added a splitter with valves, and now the sump-pump pumps 65% to fishtank and 35% to the NFT snake - hope that answers the question, and thanks very much for your 2 cents!!

-n

Vlad Jovanovic said:

My 2 cents...

1) "Best" size holes (and spacings) will depend on what you are growing. No need for 3" net pots for short term small crops like lettuce, basil etc...

2) I like to use/order net pots from these guys http://www.hydroponics.net/c/166 the 'grow-pro' pots all have a 1/8" lip...so if you order a 2" net pot you can use a 2" hole saw and not have the pot fall through (since the top of the net pots outside diameter is then 2-1/4" ). They are more durable than some of the other net pots I've used/bought...and they don't seem to come with as many quirky manufacturing fuck-ups (like poorly molded plastic on the bottom of the pots, or bottoms being practically solid with plastic instead of nice defined slits for the roots to grow through). 

They're pretty quick to process and deliver orders as well, which is always nice.

3) and 4)  The slope and flow rate can be pretty important. Although this may play out differently in the "homespun round PVC pipe" type of NFT rig that most folks here seem to like to use. Normally the NFT gulley's are flat bottomed and you really only would want a very thin film of water moving through at about 1 litre per minute. Dr. Coopers recommended slope of 1:100 seems pretty unrealistic for us 'normal' folks using crappy materials in less than perfect conditions/physical environments. But 1:50, 1:40 or even 1:30 is usually totally doable.

I imagine that in a round PVC pipe you'd have a much bigger volume of water in there, but would still not want the water to be whizzing on by the roots too quickly...(in classic flat bottomed NFT it has been reported that anything much beyond a flow rate of 2 litres per minute, seems to cause some deficiency issues...So play around a bit

Is that NFT rig in your pics fed directly from your fish tank with no pre-filtration? 

[Vlad Jovanovic]

Very cool. 'Clean'-ish water seems pretty important for NFT to work well long term in AP (or organic hydro where you also have solids and fines to deal with)...

3-5 degrees seems like a bit much (not that it might not work just fine or anything...a slope of 1:30 works out to just under 2 degrees). 

If you happen to find that the pumps 35% is too much...just "T" it off with a ball valve so that you can regulate the flow. it might be nice to have that option as the weather/seasons change or whatever...

Good luck. Nice looking system BTW :)

Nick Scud said:

Vlad - the NFT snake is fed from the SUMP - meaning the water has already drained through the grow-beds and is returned to the sump - the sump pump originally pumped water ONLY into the fishtank, however I added a splitter with valves, and now the sump-pump pumps 65% to fishtank and 35% to the NFT snake - hope that answers the question, and thanks very much for your 2 cents!!

-n

Vlad Jovanovic said:

My 2 cents...

1) "Best" size holes (and spacings) will depend on what you are growing. No need for 3" net pots for short term small crops like lettuce, basil etc...

2) I like to use/order net pots from these guys http://www.hydroponics.net/c/166 the 'grow-pro' pots all have a 1/8" lip...so if you order a 2" net pot you can use a 2" hole saw and not have the pot fall through (since the top of the net pots outside diameter is then 2-1/4" ). They are more durable than some of the other net pots I've used/bought...and they don't seem to come with as many quirky manufacturing fuck-ups (like poorly molded plastic on the bottom of the pots, or bottoms being practically solid with plastic instead of nice defined slits for the roots to grow through). 

They're pretty quick to process and deliver orders as well, which is always nice.

3) and 4)  The slope and flow rate can be pretty important. Although this may play out differently in the "homespun round PVC pipe" type of NFT rig that most folks here seem to like to use. Normally the NFT gulley's are flat bottomed and you really only would want a very thin film of water moving through at about 1 litre per minute. Dr. Coopers recommended slope of 1:100 seems pretty unrealistic for us 'normal' folks using crappy materials in less than perfect conditions/physical environments. But 1:50, 1:40 or even 1:30 is usually totally doable.

I imagine that in a round PVC pipe you'd have a much bigger volume of water in there, but would still not want the water to be whizzing on by the roots too quickly...(in classic flat bottomed NFT it has been reported that anything much beyond a flow rate of 2 litres per minute, seems to cause some deficiency issues...So play around a bit

Is that NFT rig in your pics fed directly from your fish tank with no pre-filtration?