Hydroponics (DWC) Newbie
 

Hello everybody, I am new to this forum and also new to hydroponics. I am from Singapore and due to limited space here the interest towards indoor gardening.
I have a DWC setup with 6 small pots. Have lettuce and bell pepper in 3 each. It's been 3 weeks now and the seeds took 3-4 days to sprout after which I moved them I to DWC. The seedlings are in a sponge substrate held together in a netted pot by hydroton clay balls.

I record the PH, PPM, temperature everyday twice
On an average PH is 6.5 - 6.6, PPM is 1380 a 1400, temp is 29deg C to 31 deg C

I used my aquarium lights which are 36w x 2 with 7100K each
Also I see the seedlings are green and there is 3rd and 4th leave sprouting.

It's 3rd week and I don't see the roots coming out of the sponge media as I notice in some other threads where roots are flourishing out of the netted pots.

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ur ph target should be 5.6-6.2
take it once a day, along with ec and min/max temperature and humidity
ditch the dwc and get a fogger off of ebay to make an aeroponic system. much better, especially for seedlings and clones
is light getting at the root chamber?

Hello atulbaliga,
Water culture systems are very good for starting seedlings, but there are a lot of variables. I have a feeling that you haven't seen roots coming out the bottom mostly because of the sponge cube. Some sponge materials can be hard for the roots to grow through, and just take longer to do so.

With that said I have some other concerns.

1. It's hard to tell in the pictures but at least one of those pictures looks like one of those sponge cubes is saturated with water. The sponge material should be damp but not soaked. Some sponge materials soak up moisture easy and others not at all. So the actual material you used for your sponge cubes could be a problem not only because it may be tough for the roots to get through, but also because it may be sucking up to much water.

2. Related to #1, your water level may be to high causing your cubes to become saturated. Again the type of sponge material is going to be a huge factor in how much water it sucks up.

3. Your nutrient concentrations are to high for seedlings that small. For seedlings that small I wouldn't use anything more than 1/4 strength.

4. I agree your pH is slightly high, not too much, but I would try and get it down closer to 6.0

5. Your water temp is to high, especially for the lettuce that is a cool weather plant. You want to get your water temps closer to 70-75 F ( 21-24 C). High water temps cause heat stress for the plants, and is especially hard on delicate seedlings.

5. Your lighting may be adequate for now provided the bulbs are close enough to the plants, but will need to upgraded once they get bigger than seedlings.

P.S.
Using foggers can be problematic and tend to have issues. First they have been known to increase the odds of fungus and fungal disease on the roots. Second while the fog can look thick, there is very little actual moisture in it. The fog is basically dry and can very easily deprive the roots/plants from getting moisture they need, especially the bigger the plants get. Third the pads can easily clog and need replacement very often. Make sure to get Teflon pads if you do because the Teflon pads don't clog as easily.

Thank You GPSFrontier for the valuable comments. Will work on the PH. As of today, the Lettuce has withered off and I am left with Bell Peppers. I will start another setup for Lettuce following your guidelines.
The sponge was purchased by a local hydroponics equipment manufacturer selling starter kits.

Your site http://www.homehydrosystems.com/ is my bible and have the nutrient requirement chart printed out for reference. I derived the need for PPM and PH from there. Guess its for older plants and for seedlings we should go by 1/4th rule :)

To give you more info of mysetup, here are the pics
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For Bellpepper, I see a small root out of the sponge. Will monitor the progress and report back here.

I don't see any dome over it. If you put a disposable clear plastic party cup upside down over each of the seedlings it will help hold in the humidity. I would put a few small holes in each of the cup domes to allow fresh air to circulate from the bubbles underneath up into the cups and out the holes.

Hello atulbaliga,
I'm glad to hear you find my site useful, I try to update and add to it regularly.

Yes the values in the charts are for larger plants. The values in the charts are also only a starting point guide. There are lots of variables that will affect a plants nutrient uptake, and it would be impossible create a chart that could include every possible variable. Even the amount of light, temperature, and humidity will change how a plant uses nutrients. Not to mention the specific variety of the plant in any plant category. So the charts are meant to be a general starting point.

With pH, right around 6.0 really works for just about all hydroponically grown plants. Some plants may benefit from a little higher pH, like with peppers. Some spicy pepper plants increase heat with higher pH. But you never want to go above 7.0, and 6.6 is right on the edge of that. pH doesn't need to be exact, you just want to be within a range. Most plants fall between 5.5 and 6.5 for good nutrient uptake. So if you shoot for right in the middle at 6.0 it doesn't mater if it vears some. If your growing hot peppers and like them as hot as you can get them, closer to 6.5 while their fruiting could help that. But if it gets above 7.0 then the plants could suffer from nutrient deficiencies.

As for the nutrient concentrations and seedlings, yes absolutely, seedlings don't need full strength nutrients. That's kind of like giving a baby that eats baby food a 7 coarse meal. Theirs no way a baby could eat a 7 coarse meal. He would take a few bites and the rest would be in the trash. If he tried to eat it all, he would get sick or bloated. In fact for seedlings as small as the one's in the pictures you posted, I typically don't even use any nutrients at all until they reach that size. Then start with something like anywhere from 10% to 25% strength. Then in a week or two when they bigger, I'll increase it to about 50% strength, and so on....

Want to provide an update on corrections and learning from the comments. I calibrated the PH to 6.0

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Hello atulbaliga,
When you say calibrated pH, are you referring to calibrating a pH meter? Or adjusting the nutrient solution pH? I asked because I'm not sure what the liquid in the picture is. I assumed you were using a pH meter because because of the values you were giving, but the picture looks like the color you would get using pH drops at 6.0. So now I'm wondering if the picture is on the calibration fluid used to calibrate a pH meter, or of the pH drops test.


Also have you gotten the water temp down?

Sorry for the confusion. I adjusted the nutrient solution to get the PH to 6.0. As a backup I also use the tetra PH test kit to verify and this pic is the output of the test after adjustment. PH meter needs frequent calibration as its a Chinese make and you know how reliable they are 😜

Water temp is still at 28 deg C and humidity has risen up to 78% RH. Planning to put a fan around to circulate the air and also cool the water.

Ya, I don't trust the meters, the drops are much more reliable and cost much less money, so I don't even bother with the pH meters. I would put some ice in that water to drop the water temp down another 10 degrees to about 72 F (22 C).

I did that today morning. Put in a few ice cubes in the water to bring the temp to 21 deg C.

PH at 6 but water temperature at 26 deg C. More ice to cool the water 😉

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Update on the growth. PH at 6, using ice to cool the water. No nutrient added. Covered with stroyfoam to avoid evaporation. The pots completely covered are empty.

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how much ice do you need and how big is the reservoir and do you have any temperature data for me? this information will be useful to me

How much water is disappearing that your concerned with water evaporation?

I don't think the evaporation is very high. Haven't actually measured the quantity periodically.
I have 7 lts of water in there and I put in about 500ml of ice everyday. Need to remove the water daily as ice adds in additional water😀

Do these leaves look healthy?

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That's what I figured, with plants that small they aren't drinking much water yet. So I figured you would have the opposite problem. Instead of loosing water through evaporation, you would have excess water building up because the plants aren't big enough to drink up as much as you add back in ice daily. So I'm confused as to why you would want to cover the openings with the Styrofoam to try and block evaporation? I don't think it will hurt anything, but I don't see it helping anything either.

P.S. chopficaro
I'm currently working on a new article for the website about the importance of the nutrient solution temperature titled "Your Nutrient Solution Temperature is Important" that I expect to be done with in a few days. I'll post a link to it for you if you want.

Sorry atulbaliga, you asked a question and I forgot to reply to it. Yes they look pretty healthy. They might be slightly yellow, but that may simply be because they are very young leaves. It also might just be the picture itself. But yes from the top they look pretty healthy. Are the roots nice and white too?

Update since last post. Pepper plants are healthy and growing.

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Ppm at 1100 and PH maintains 6-6.5. Temperature is the tough part as its humid and a tropical weather. 28-30 degC is minimum.