My first ebb and flow

[halfway]

Ok, replaced the spent solution with clean water and let it "rinse" the system for 24 hours. I emptied that and added fresh water with full solution this morning which is at the 3 week mark.

I think it was time as some of the new growth on the basil is lighter green than they should be.

I also notice the roots of both the lettuce and the basil are not nearly as white as they have been.

I do not see any other signs of distress in the roots or the veg growth.

Should I be conserned with the dulling of the roots from white to almost a brownish haze?

Thanks in advance.

[GpsFrontier]

Ya,
I always try to stress observation of the plants as the most important factor in knowing how they are doing. Just like you noticed the leaves starting to become yellow. I used to mark when I changed the nutrients on the calender, and/or added anything to it (and still try to). But after forgetting so many times, I mostly just rely on observation to tell me when to change them. Although knowing when it was changed last is still important, because as you get used to knowing how long the plants can go without problems (including pH swings), signs of early problems can be a singe of other issues.

The roots looked nice to me. Although I did see some slight brownish, but that is not necessarily a sign of any problems. Older roots will tend to become brownish naturally, also the nutrients in the solution tend to stain the roots the older they get. As long as you are continuing to get good new growth, and the new roots are continuing to grow out white, and the older roots are not turning dark brown, as well as the tops of the plants are looking good, then that wouldn't be anything I would worry about.

If they do start to turn dark brown, the two major factors that I know of is "lack of oxygen in the water", and "excessive nutrient temperatures". Of coarse dark brown mushy roots could be caused by pathogens that can cause root diseases also, as well as fungal diseases, but I have not ever come across that specific problem. Like I said, I clean and flush my systems to prevent that sort of thing. But I have dealt with "excessive nutrient temperatures" (I live in the mojave desert). But I would consider the two major factors first.

I always keep an eye on the nutrient temp just in case, it should be be between 68 and 72 degrees Fahrenheit optimally. Above 80 and your likely to see signs of browning as well as dissolved oxygen loss in the water. Below 60 and the plants wont be able to absorb the nutrients as well, and your likely to see signs of stunted growth. Because I grow outside my nutrient temps have ranged from 110 in summer, to about 38 in winter, so I have seen extremes and dealt with both.

I also add H2O2 (hydrogen peroxide), not really for pathogen/fungal control, but for adding extra dissolved oxygen. But it can help reduce the number of pathogens in the solution also if you ever come across it. I use 1 tsp (5mL) per gallon each week (when I remember). Sometimes I forget when I added it because I didn't write it down, so I will wait to add more so I don't add too much in too short of a time.

P.S. Just thought I would mention that when I flush my systems with straight water with each nutrient change, I usually just run it through a couple of cycles (30 min each or so). Then sometimes I empty that out and do it again, before emptying that to add the fresh nutrient solution. But I don't think flushing it for 24 hours will hurt anything.

[GpsFrontier]

Just thought I would post a some pictures of brown roots that were caused by excessively high nutrient water temp. If I remember correctly the nutrient temp was in the upper 80's and low 90's at the time of the pictures. They are the roots of the strawberry's that I grew 2 summers ago, and the pictures were taken in either late May or early June. Our temps in early June reach in upper 90's and by late June they are in the 100's (I grow everything outside). I sent the pics to General Hydroponics tech support, who told me it was caused by the nutrient temp. That's when I first learned that the nutrient temp was important.

I then froze blocks of ice to cool down the nutrient solution with, I then saw new roots coming out a nice white like they were supposed to be. I needed to add ice blocks twice a day, once in early morning, and again in mid afternoon. Even so, the nutrient temp would fluctuate and I couldn't keep it within range constitutionally. By early July the daytime temps constitutionally reach the 110 degree mark, and I was simply not able to keep up with freezing the amount of ice I needed. With all the containers of water jam packed in the freezer absorbing all the cold, the ice creme was getting soft and melting (even on the highest setting). So I gave up on my first summertime attempt at hydroponics.

I know you are growing inside and are very unlikely to see anything like those nutrient temperatures, and I didn't post the pictures to scare you. But I had the pictures, and thought it might be helpful to see what happens when the roots of a plant are constitutionally subject to high temps for future reference.

[halfway]

Very helpful post and it doesn't scare me in the least. That is good to know because mine are just lightly brown. It was enough to notice after they had been brilliant white.

Thanks for sharing the experience. I believe your "underground" water holding tank is designed to offset the heat right?

[GpsFrontier]

Ya,
Ever scene I had that problem, I have been on a quest to find economical ways to cool the nutrient selution. The in-ground reservoir (geothermal reservoir) was the only realistic economical option I found. Just about every other option involves using a lot of electricity, and with $700 electric bills during summer (because of running AC 24/7) adding much more to the bill is not really economical for me. The design works as intended with ease of use in mind. Although I never really finished it. I had planed to build up the above ground portion because I was not able to get the hole as deep as I wanted (too much rock in the ground here). I also never really completed insulating the above ground tubing, and plant buckets that I Had intended to do. But never the less, the nutrient temperature remained pretty constant between 80 and 84 degrees thought the hottest part of the summer (late July and August), and I never added any ice to it at all.

That's about 10-12 degrees warmer than perfect. So despite the fact it could have been better if I didn't get lazy, I think it preformed quite well. I also know next summer I can make it better by not being lazy, and finishing up the details. I also have two new ideas to test next year. Both work on cooling by evaporation, but in different ways. One is relativity easy and inexpensive to build. The other will take some more research, as well as small scale testing and refining in order to see if it's feasible and what it would take on a larger scale.

The first one was built by a guy in Phoenix where they get the same type of daily temperatures we do here (phoenix is about a 4 hour drive), and he clams it works well. He sent me pictures of it with details, but I don't want to post his pics because I never asked if he would mind. But When I build it I will be happy to post all the details of how I did it. Also I may draw up some 3-D pictures to post asap for people if there is any interest.

[halfway]

Time for an update.

We have been steadily harvesting over the past few weeks and the lettuce and basil have been excellent.

I didn't see a noticeable change with lighting above 13 hours so that is where I have kept it. The lights remain about 2-3 inches above the plants and the fan pushes the little heat generated out of the way. Without the fan it hits around 82 degrees, with the fan it stays around 68. Perfect for crisp, tender greens.

The browning in the roots I posted about earlier still remains, but many new and bright white roots have grown around them and from the sides of the pots. I may have created a little root shock OR it occurred from holding the nutrient change from 2 weeks to 3 weeks. The plants were not effected at all, so I will remain at 3 weeks for initial nute changes with lettuce in this system. I did notice a slight decrease in color at around 20 days, so 3 week nute changes it is.

Since 5 pots grow Simpson lettuce and 1 is growing basil, I have a need to keep crops in rotation as discussed by hydrogardener here and in HIS blog. He has a great system that I am using as somewhat a template for keeping us in rotation. Many others' methods are incorporated as well.

I am building 2 DWC systems for lettuce rotations and still debating the future use of this ebb and flow. The determining factors include the size of plants as I need to keep the floros on them at a uniform spacing. Keeping the basil horizontal is a challenge!!

Here is a pic from November 27th. This is after many harvests.

[GpsFrontier]

Hello halfway,
Sounds like the plants are doing good. I'm not surprised at the basil, the basil that I grew got about 1 foot tall and 1 foot wide before I pulled the plug on it because I wasn't able to keep the nutrient/water temperature under control any more, so I'm not sure how big it would have gotten. 68 degrees is a great temp for growing lettuce. I wish I had a basement where I could grow year round lettuce greens like that.

Just wondering, how deep is the water culture systems for the lettuce that your building planed to be. Mine did great in a regular water culture system, with the water only being 3-4 inches deep. Although the deeper it is, the more of what I call buffer water (nutrients) there will be. That could allow for longer intervals between nutrient changes, provided you keep them fresh by not allowing to much algae and other things like unwanted pathogens to grow in it. Good aeration of the water, water circulation, blocking light and keeping the water in the right temperature range will help a lot in keeping them fresh as long as possible. In a water culture system (deep or not) when there's no water pump circulating water, an air pump and bubbles from air stones keep the water moving (circulating), as well as aerate the water. So the more bubbles, the more movement the better. Especially when trying to keep them fresh for longer periods. But for me, I don't think there's a need, or even much benefit for it being deep just for lettuce.