My NFT Setup March 22 update
 

this its going really well to be my 1st time :)

I few problems that had to be resolved..its up and running....

here its a video

hydroponics

Cool video, the plants look like they have really taken off. Lettuce is a fairly fast growing plant, and it looks as though that is exactly what they are doing. I see a pepper plant in there also, and the strawberry plant looks bigger too. My lettuce plants are growing very fast also. There roots are somewhat brown, and I'm not exactly sure why. But they are growing very nicely, so I haven't been concerned about it yet. I plan to post pictures of them later this week, at the two week point from the last pictures (on the 24th).

Thanks.. yes they are growing fast!! The pepper and the strawberry are there until I finish the other system... it would be a dripper, non recirculating on plastic bags.

I just got a cistern float valve to install it to the lettuces reservoir because next week we are going to Disney :)...
What would happens if the nutrients and the PH goes a little crazy during that time?

That would depend on how crazy it got. With the float valve setup (assuming the water is the right temp and pH) the only real hazard would be the solution getting diluted, or it not functioning correctly while you were gone. I'm not sure if you are going to have the line to the valve come from a household tap, or another container (secondary reservoir) with the water in it. If you use a separate container you can fill that container with just fresh water at the right pH, or if your concerned about diluting the main reservoir you can fill the secondary reservoir with a diluted solution of pH balanced fresh nutrient solution.

That way the water that is replaced wont dilute the main reservoir as much. But you will need to make sure that the diluted replacement nutrient solution is not too strong, or it will make the solution in the main reservoir too strong. I would probably make the replacement nutrient strength about 1/4 strength. If the water line to the float is coming directly from the household tap/line, you wont be able to do anything about adding replacement nutrients or pH levels of the replacement water. You can check the tap water and see what the pH is usually (ours changes from time to time).

Also, if possible you can add extra nutrient solution to the main reservoir. That way it wont get diluted as much when fresh water is added, because there is more nutrient solution (buffer) to dilute. Also you can set the float at a level so it will only add fresh water when the nutrient solution goes below a certain point. Like say it drops by 3 gallons (depending on the size of your reservoir), then it will start adding fresh water. That way the nutrient solution becomes a little more concentrated before the float opens and fresh plain water starts diluting it.

Thanks... It would be from the tap... another question... if it gets really diluted.. could the plants die in that week? or just stop growing

Starting with fresh nutrients I seriously doubt you will have a significant problem in just a week. Unless your plants are drinking up a lot of water, and you are replacing it quickly. I have had plants using a 10 gallon reservoir, and replacing 2 gallons of fresh water daily. That would be about 14 gallons of fresh water to a 10 gallon nutrient solution in one week. Without much in the way of noticeable effects. I did need to adjust the pH every other day or so though. Also, I let the same reservoir go for 2 weeks at a time before changing the nutrient solution, but at about the one week point I would add maybe 3 gallons worth of full strength nutrient solution instead of just plain water.

If the plants are deprived from nutrition, the plants will slow down in growing. Then if it gets sever enough they could die, but not in a week when starting from fresh nutrients. They may slow down a little near the end of the week. I don't think you are adding nutrients daily now, so there would be no real concerns while you are gone. But at most they might slow down a bit.

The thing I would be concerned with is pH, if the pH level goes out of range, it wont really mater if you have good nutrients or not, because the plants wont be able to access them. If you are adding tap water now and not needing to adjust pH much I don't think you will have a problem. If when adding replacement water, your water pH was a little high, and you were adding pH down to compensate a couple of times during a one weeks period. Then you may want to leave the pH a little low to begin with. That way as fresh water replaced the used nutrient solution, the pH level would rise because of the pH level of the fresh water that was being added.

Update

all the plants survived.. but the lettuce now its really bitter... what could be a reason?

This is an indication of the plant preparing to go to seed cycle.They'll start bolting if they haven't yet. They increase repulsive active substances (against natural enemies) to protect their genetic reproduction. Heat promotes bolting cycle as well.

which means I lost them :(

You can always try to put them in the fridge for a few days (as long as they keep fresh) and try again. I've heard that that the bitterness may vanish or get less intense. No warranty, it's worth a try. You can also cook it in with some dish where the bitterness doesn't matter or is welcome. We use often a few leafs in noodle soup.

Fact is that lettuce likes cool climate but there are some that tolerate the heat better and will not bolt that early. Try more varieties in the future. I have some Korean and Portuguese varieties growing now that seem to cope well with the actual 38.5°C! My nutrients are at 33.4 °C and that doesn't seem to bother them either :confused:

Vale, vale... :)