Yellowing Spotted Plants!

These little ones are about to reach the end of week three. The first sets of leaves are beginning to yellow severely with brownish spots. It's starting to show signs on the newer sets of leaves as well.

They are on a 24 hour light cycle in a DWC system.

What I'm reading, it might be a magnesium deficiency. But I can't really diagnose since I have no experience.

The last res I put in 1.3 ml of micro and 2.5 ml of bloom. (They're in about 8 gallons of water).

Some help would be greatly appreciated!

Youre probably going to need some proper hydroponic nutrients that are for the growth phase of plants. Bloom is for when you switch them to flowering.

In DWC and all other types of hydro growing you need the following to be fairly close to accurate.

- pH between 5.5 and 6.0
- PPM at about 450 for where you are at now
- an air stone to keep the water airated (very important)
- vegging nutrient that caters for hydroponic growing
- water temperatures no higher than about 72f

So starting with the correct nutrient, dump the res and reload it with the right nutes, pH and PPMs and it should bounce back in no time.

im having similar problems but i have no access to hydro shops in my area (england is crap for that) does anyone know any net sites i can get a good veg nute from?
also here is a very noobie question but how do i measure ppm?

Youre basically looking for a grow nutrient that has a higher ratio of nitrogen (n) than phosphorous (p) and potassium (k). So if you look on the labels on the bottles you will see the NPK rating something like 3:1:2 which means 3 parts nitrogen, 1 part phosphorous and 2 parts potassium. Also a good nutrient will have a full range of micronutrients in it too like calcium, iron, manganese, magnesium etc.

PPMs or parts per million is the strength of the nutrient. Its important that in hydro growing that you don't over or under nutrient your plants. After a while you can do this by eye but in the beginning its better to use a PPM meter.

Id start new clones at about 250PPM, then gradually raise it to 450PPM by end of week two, then 600PPM by day 21. Watching how your plants react.

I also eventually add a bit of fulvic acid to the mix to help uptake of nutrients.

Thanks for the reply, Jonus! I'm really at a loss here on the nutrient issue. I've been putting off buying a TDS meter but it looks like I need to break down and buy one.

Last res I put double that amount and got some nute burn. I put about half the recommended quantity, so this last res I did 1/4 the recommended. I'm using GH flora series, which everyone recommended, but should I switch to something else? Or should I add gro instead of just micro and bloom?

Thanks so much!

Yeah the point I was making was about the grow vs bloom nutrients. You are trying to grow your plants not bud them yet, so you need to be feeding them the grow nutrients. Getting the strength right will take some time and eventually you will be able to read your plants from just doing it a lot.

The other way is to grow by the numbers (as I listed above) in which hydroponics DWC is about the best way to do it since when things go wrong, they can really go wrong and fast, but when you get the numbers right, your plants will flourish.