DWC Starter help

I want to start a DWC but not really sure on some stuff so I want to ask for opinions. Grow tent I will use a 40x40x100cm, as bucket will be using a 5 litre bucket for starter and maybe change to a bigger bucket if needed later on (Most probably yes), lighting I will use 450w viparspectra led (has both veg and bloom options) and as nutrients I will be using general hydroponic gro bloom and micro. I got a tds meter today and checked the tap water and it was reading 780ppm, I was a lot of posts about what ppm should be but everyone was stating differently so want to ask here for a definitive answer and one last thing is how should I mix the nutes and when should I change the total water?

So 5 questions -

Is 5 litre enough to start?
What is the best ppm I should use for seedlings and later stage of growth
Whats the best way to get the ppm down without RO?
How should I mix the nutes from seedling, week 1, week 2 etc.
When should I change the total water nutrients mixture inside the bucket?

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Your set up is similar to mine - I have 3.5ga pots, however.

I grew from seed in a seed starter, then transplanted to my DWC pots when they were seedlings. Filled the bucket to two inches below the net pot. During early veg I kept the nutes super low. I followed this nutrient schedule (I didn’t know about PPMs until much later in my grow):

When I figured out what PPMs are, I switched to the GH PPM chart for DWC/recirculating:


I think you can certainly start your plant in a 5 liter bucket, but you will want to get a bigger bucket at some point (I would just watch root development and decide based on that). With the 5 liter bucket you would be adding water every single day. With 3.5 gallon buckets my plants need to be topped off every two days during late veg and flower.

What is the PPM of your water to start? You might not need to worry about lowering PPM early on. My tap water runs at PPM 65 out of the gate.

Follow the charts above to determine nutrient mix - err on the side of FEWER nutrients in the veg stage (IMHO).

I change out my buckets completely every seven days. During veg I topped off with PH’d water (no nutes added) once or twice per week. During flower I have topped off with PHd water with nutrients in it to keep PPM where I want it.

Hopefully that answers some of your questions.

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Thanks for your reply Bogleg you did answer many questions I didn’t write, appreciate the in depth answer. But can I ask something, why do you put the water 2 inches below the pots? How will the plant take up the nutrients or am I missing something here?

Thanks in advance

The theory is (and it seemed to work for me) that you want your plants’ roots to have to reach for the water. By keeping the water a little out of reach, the plant will develop stronger root structures to get to the water. This will also make sure you keep water away from your grow medium, preventing and rot/mold/etc from occurring where you can’t really see it.

One of the things I LOVE about growing hydro is that I can visually check the roots.

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I will add one thing - the less volume of water you are adjusting, the harder it is. It’s much easier to add nutes and adjust PH on 5 gallons of water than it is one, simply because the amounts you are putting in, especially during veg, are so small. I invested in a set of syringes (5ml to 30ml) with long needles (so I can get all the way into the nutrient bottles). Doing it with the syringes is 1000 times easier than trying to use a teaspoon measuring spoon.

I just now noticed that you actually stated your tap water PPM. 780 is REALLY high. I’ll have to let someone with more experience/smarts than me weigh in on what to do about that. One potential option that I have been using for the last 4 weeks of my current grow, is using water from a dehumidifier. There is mixed messaging all over the internet on the viability and safety of using condensate from a dehumidifier for watering plants, but all of the hard science I could find on it said it would be totally acceptable. The condensate I collect and use in my DWC system is generally PH 6.3 and PPM 25 before I do anything to it. If you have a dehumidifier, you might consider harvesting water from it for your grow. That being said, I strongly caveat this. Do your own research and decide for yourself if that’s a route you want to go.

On this one I agree with you, I do use dehumidified water for the soil plants but wasn’t sure about DWC. Will definitely try it out. About the bucket I read that aswell I will take it in consideration to use a bigger bucket. I do have a set of syringe for that matter, but do I add nutes directly in the water when the plant is in growth stage? And yeah I was wondering about the ppm straight from the tap, yous is amazing for growth with 65ppm.

This is how I do my nutes:

  1. Fill 5 gallon bucket with water (either from dehumidifer or from tap)
  2. Add nutrients in order recommended by General Hydroponics (FloraMicro first, then FloraGro and FloraBloom - I also add CaliMagic) to the 5 gallon bucket of water. Check PPM. Add more nutes if needed to get to correct PPM.
  3. Check PH
  4. Adjust PH as needed
  5. Let the bucket sit for 2-3 days
  6. Check PH
  7. Adjust as needed

During flower, where you end up using a lot of nutrients, I checked the PH and PPM of each bucket in my grow. To adjust where I needed, I kept one bucket of PH’d water with no nutrients, and one with nutrients. I add water with or without nutes to get the PPM in that particular bucket in a range I like. For example, if I check one of my buckets and the PPM is at 700PPM, I added 950PPM water to it. If it’s at, say, 1.2k PPM, I add water with no nutes to it. This has generally kept me where I want to be in late flower (950 is where I try to stay).

On the days I change out the water completely, I use a siphon pump to pump out the remaining water in the buckets, then use the pump to pump in replacement water. A siphon pump was necessary for me because I made the rookie mistake of putting too many plants in my tent, then putting a trellis over them… so I can’t move them at all.

So I can mix the nutes before using it? Because I read to not mix until right before using?

And how much do you add in the mixture if the ppm is not right?

Sorry if I’m being annoying with so many question.

The just don’t want you to mix the nutrients together and THEN add it to the water. Adding the nutes to your water and letting it sit around isn’t a problem. For example you have your bucket of water, you add nutes to it like I described above… totally fine.

As far as PPM, I only monitored that during flowering. I stayed with the “3-2-1” ratio for the GH 3-part (Micro/Grow/Bloom), which is basically 3 parts Bloom, 2 parts Micro, 1 part Grow/CaliMagic. To give you some real numbers:

During the late flower stage (before ripening), I was using the chart I posted above, and putting these nutrients in my water (per gallon):

15ml FloraBloom
7.5ml FloraMicro
2.5ml CaliMagic

That is a ratio of 2:1 Bloom to Micro.

So let’s say that I’ve added that per gallon to my water, and my PPM comes out to 700 PPM. I want to get up to 950PPM, so I will add 2ml of FloraBloom and 1ml of FloraMicro, check again, and keep doing that until I get to where I want my PPM to be.

Clear as mud? Basically once you figure out the ratios of nutrients you are adding, you can just use that ratio and add as much as needed to get PPM where you want.

That’s how I have done it, but I am at the end of my first grow, so hopefully a more experienced person will chime in.

You’ve been very helpful thanks, will post progress later on months.

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Happy growing, and happier harvesting!

One more thing from me - for tap water with high PPM, I think you can let it sit out for a few days and the PPM will go down (chlorine, etc. will evaporate out of the water). So you might consider trying that out and testing it to see what your PPM ends up being after a few days of resting your water.

I was thinking about trying that or else I mix in potable water/dehumidified water so that I can try to level out the ppm, potable water has a ppm of 65 so I think that should work what do you think?

To get to a baseline you can work with, that will certainly work. Just don’t confuse PPM with the proper nutrients for your plants. You could draw 700 PPM water from your tap, and your plants could be in a life cycle that requires 700 PPM, but that doesn’t mean that the water straight from your tap has the RIGHT nutrients in it. So you really want to get PPM as low as possible, then add your nutrients to get to the PPM you want for your plants.

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Yeahhh finally I understand what you’re saying, I’ve been searching every where to try to understand that but thanks to you I got it. So for example if the plants needs 700ppm nutes, that means that only nutrients not the tap water ppm combined, you’ve been of great help bogleg.

Happy to help. Keep this in mind:

The PPM numbers you see in the chart I posted in my first reply for reach stage of the plant’s life are the TOTAL PPM that you should strive for.

For example, let’s say you are in mid bloom and you want to have a PPM of 1000. Now let’s say that you are using tap water that has a PPM of 100. You still want your PPM to end up being 1000, so you need to add enough nutrients to make up 900 PPM. This is why monitoring PPM is more accurate than just using the amounts arbitrarily listed in most of the nutrient schedules (i.e. the first chart I posted).

Of course this makes it a somewhat moving target because your water source might not always be exactly the same PPM. In the case of the condensate from the dehumidifier, it will generally be very close. Mine is always between 25-29 PPM.

If you don’t have enough dehumidifier water or don’t have one, you can buy RO or distilled water to mix with your tap water. If tap is 700 and you want 350, mix it 50:50 to get 350.

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Sorry for the late reply was busy with work, that’s some great explanation, really appreciate all your effort for trying to help me.

Can I use normal drinking water instead? it’s much cheaper than distilled and I have plenty