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My first setup - NFT and Ebb and Flow

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Old 11-06-2013, 01:18 PM
ghostpepperstore ghostpepperstore is offline
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Join Date: Nov 2013
Location: St. Louis Metro Area
Posts: 3
Default My first setup - NFT and Ebb and Flow

First off, hello everyone, this is my first post here. I am a professional grower that specializes in super hot peppers, but I also grow all types of vegetables for local markets. I have dabbled with DWC a little in the past, but never anything on the scale of which I am about to embark.

Due to some really inconsistent weather this year, our field grown lettuce was less than predictable so I made the investment into a 8-channel, 144 spot NFT system, a 4' x 8' x 7" flood table and a 4' x 4' x 7" flood table. All of these are located in my 14' x 16' greenhouse just outside of St. Louis. The hope is to supplement our weekly farmer's market sales with a bit of lettuce each week.

Untitled by GhostPepperStore.com, on Flickr

Unfortunately I do not have pictures of the flood tables right now, but I will come back and update with those and pictures of the NFT which is now plumbed on both sides.

The NFT setup is using a underground reservoir, which I thought would help with both algae growth and keeping the water temperatures down. I have a 1000gph pump which, surprisingly, is only getting me about 7L/m return at the drain pipe. Each channel is fed using (2) 1/4" microtube with an inline adjustable flow valve.

I will be using the smaller flood table to start my lettuce/spinach seedlings in 1.5" rockwool cubes then transfer them to the NFT once the roots are coming through the bottom. This tray will also double as a starting area for some of the other veggies in the Spring since it is quite an overkill since I will only be starting about 20 lettuce seeds each week.

I also have a 1000w MH light mounted centrally to provide supplemental light during the shorter days, I plan to keep it to about 14 hours/day. The greenhouse is heated and I keep night temperatures at around 62 degrees. Daytime temperatures, except in the Summer, stay below 85. I have invested in a pH meter and EC/TDS meter but at the moment I will be using tap water which is testing at 7.5 pH and 250ppm. I do not plan to change to RO water unless absolutely necessary.

So now for the questions.

This is my first time using rockwool. I sowed 8 varieties of lettuce, spinach and some herbs in the cubes on Sunday after soaking the rockwool in a 5.5pH bath. This morning, the cubes are still very wet. Is this normal? I realize the seedlings are not using any of the water yet, but since I will be giving these the flood and drain treatment, it concerns me that the cubes are staying wet for so long. The cubes are not covered since I have decent humidity in the greenhouse this time of year and it has been raining for the last couple of days to boot.

I know that for most NFT systems the recommended flow rate is 1L/minute per channel. I am not quite getting that rate at the moment, is this going to be an issue?

I am totally open to constructive criticism here, so please, if you see something wrong with my techniques, call it out.

Sorry for the long first post! Thanks for reading.

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Old 11-14-2013, 01:28 AM
Mattm Mattm is offline
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Join Date: Jun 2012
Location: Florida Keys
Posts: 16

Yourr plans sound great. Keep posting pics.

I use an nft system for tomatoes and have used both 1.5 rockwool cubes and oasis cubes. Both have worked well but I like oasis better.

I soak my cubes for 24 hrs the night before seeding. Mine are soaked in my reservoir that has water and nutrients. I transfer to a 10 20 plastic tray and the cubes are soaked.

I never had a problem with soaking wet cubes. I have never measured my flow into my troughs, some of my troughs have ball valves some just have open barbs, I haven't had problems with flow whether it is too strong or too weak, when my root system gets too thick and water starts dripping from intake end I adjust pitch of troughs

My toughs are 12 foot in length and 3 inches deep and I use a 90 watt danner supreme mag drive which is more than enough flow for four troughs.

Sorry about the spelling I'm trying to type on a tablet

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Old 11-14-2013, 10:58 AM
ghostpepperstore ghostpepperstore is offline
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Join Date: Nov 2013
Location: St. Louis Metro Area
Posts: 3

Well here are some pictures of the setup completely finished.

Untitled by GhostPepperStore.com, on Flickr

Untitled by GhostPepperStore.com, on Flickr

Its impossible to see the drain line in the photo, but I have a 1" PVC that runs along the floor and back into the reservoir.

Untitled by GhostPepperStore.com, on Flickr

I thought I has a photo of the NFT channels with their lids, but apparently I was wrong.

Over the last week, I have answered a few of my questions just by "trying it". The lettuce and spinach roots came through the bottom of the rockwool within a couple of days of germination and I plan to get them in the channels in the next day or two.

I am now a lot less concerned about the flow rate. After reading a few more sites, I see people running anywhere from 0.2L/m to 1L /m per channel, so I think I am going to be fine.

I had a look at some Oasis cubes that I found locally, they just seemed rather "crumbly" and I was thinking they would make a huge mess when trying to shove them into the round holes in my channel lids. I was afraid that they would clog up my drains, pumps, or feed lines.
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Old 11-23-2013, 12:29 PM
ghostpepperstore ghostpepperstore is offline
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Join Date: Nov 2013
Location: St. Louis Metro Area
Posts: 3

Time for an update!

The first round of seedlings have made it from the flood table and into the NFT.

Untitled by GhostPepperStore.com, on Flickr

The dill is particularly happy

Untitled by GhostPepperStore.com, on Flickr

Lettuce is looking pretty good too!

Untitled by GhostPepperStore.com, on Flickr

So here are the lessons I have learned so far.

Rockwool - screw it, let it just be soaking wet all the time, apparently it doesn't matter. In fact, I was only flooding my table once a day at first and I discovered that the roots coming out the bottom of the rockwool would die back as soon as they got dry. Several of the seedlings didn't have roots long enough to hit the bottom of the NFT channels when they were transplanted, so for the first few days I had to hand water those until they got their feet wet in the channel. I am now running the flood table 3x a day during daytime hours and the next round of seedlings are looking better.

Algae - Algae sucks! By the second day of running the NFT I had brown algae all over the channel. Luckily there was very little in the reservoir. I realized that the end caps on the channels had a 1/2 inch gap that was letting in enough light that algae was blooming. Once I blocked off the light, the problem has gotten any worse.

PH - My ph keeps rising and I have been having to drop it everyday by adding about 15ml of PH down to each reservoir keeping it at around 6.3. Everyday is gets back up to about 7.1 - 7.2. I am going to try a different PH down product as soon as this bottle runs out as this one doesn't seem to be very effective.
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Old 11-29-2013, 08:13 PM
fintuckyfarms fintuckyfarms is offline
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Join Date: Apr 2011
Location: Southeast Washington State - Right on the line of growing zones 6b & 7a
Posts: 347

Looks good, I use just a small amount of hydrogen peroxide to help keep the algae down.

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