Lettuce in NFT

hydro_scottyApril 4, 2010

Hey fellow hydro growers -

I am back with some questions for my NFT lettuce growing. I have been having some calcium uptake issues which created tip burn on the center of my lettuce head. I fought this for some time until I realized that I was probably leaving too many areas exposed for light to get in to the res and the nft channels. I was getting an algae infestation.

To slove this, I promptly plugged all the holes, ran a res of water and H2O2 (300 ml 35% in a 110 gal tank) for 24 hours. I promptly returned to my formula of Botanicare organic nutes-

110 gal res

400 ml pure blend grow

200 ml calplex

250 ml huvega

200 ml humex

This gave me about a 300 ppm and pH of 6 after adding some pH up.

To ensure I was killing off everything, I added 1000 mL of hygrozyme (most expensive stuff I've ever bought).

I also do everything I can to keep the res water temp below 70 with an average between 68 - 69.

Here is my issue -

My pH will NOT stay below 7 (read 7.5 this morning) after adding the hygrozyme. This is even after attempts to lower it with pH down. I have seen very little by way of information about this on the web. I will call the manufacturer later but thought I'd see if anyone here has had similar issues. I can honestly say that my plants do not look bad but I know they cannot perform at these pH levels. Also, my ppm has climbed in 1 day from 300 to 400 but I think this is due to water loss/uptake.

My roots also look wierd but can be cleaned with a simple run under the sink faucet. I am attaching a couple of pics to show that. I am also attaching a photo showing the calcium defficiency.




Any thoughts on how to control or steps to take to make sure this doesn't fall apart overnight would be appreciated. Thanks.

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Hey scotty, be careful adding the h2o2 to your res. It will kill all the beneficial bacteria in your nutrients. I had the same problem with my lettuce(calcium def.) and I remedied it with a fan blowing on the leaves. Calcium isn't mobile, so if the plant can't transpire, the calcium won't make it to the leaf tips. I'm not saying this is your problem, but if you don't have good air circulation, it could very well be.

The roots look fine. The sludge on your roots is from the PBP nutrients. I use the same brand and see the same issues.

It sounds like your doing everything right in the rez. I just added some hydrozyme to mine two days ago. I haven't had any problems with my PH. Come to think of it, my PH climbed to 6.1 from 5.8, but I only added 400ml to a 120 gallon rez. So, that could very well be the issue. I would wait a couple days, to see if it levels off. That's a ton of money in that rez. and you don't want to flush it down the toilet, using too many PH buffers. If the PH doesen't fall, you might want to do a partial rez. change, with adjusted water. Lower the PH of the new water to 5.0, to offset the rez. PH. Hope this helps.

    Bookmark   April 4, 2010 at 2:34PM
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You not a kidding about a ton of money in the res. I am hoping it doesn't take this level of treatment too often. I have tried to lower the pH about 4 - 5 times but it shoots straight back to 7.5 in less than 2 hours. Not much point in fighting it.

I have a small fan blowing over the tops of the lettuce. It isn't very big at all but I do see the leaves move so I considered it acceptable. I only started encountering this calcium issue after switching to RO water. Prior to that I just used the tap. It varied too much though as it was up to about 250 ppm out of the faucet so I switched to RO. Funny thing is, I really don't get this issue on any other lettuce outside of Romaine. It could very well be the length of leaf.

I have not fully solved the calcium issue though as it comes and goes. Even with 1:1 PBP and Calmag, i get the issue. Maybe your fan idea is worth looking into. How much air movement would you say I need? I just thought my issue may be related to algae buildup as my last harvest had very thin roots. I had left the res with some openings and some of the NFT areas open.

I just noticed that me res is now foaming horribly so I may have to back off on the concentrations.


    Bookmark   April 4, 2010 at 5:33PM
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Thanks for starting threads and reply on the related query. Thank "hydro scotty" for sharing your experienced on NFT system for lettuce growing, it's an informative thread.

    Bookmark   January 24, 2013 at 1:56AM
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