DWC noob questions - first grow

[JP12345]

I'm in the middle of researching/buying everything I need for a DWC setup and just have some questions for things that are taking up lots of internet time researching.

1) How often do I need to change my reservoir water, assuming everything is going okay? (I know this is a topic of much debate)
2) How do I actually fill/change it? I have 2x84ltr(22 US Gallons) reservoirs (thought of using an auto siphon to empty and attaching a hosepipe to my shower hose) Because of electrics, I don't want to be carrying heavy water filled reservoirs in and out of my tent
3) Am I right in thinking that I would need to fill them up to about 16 US gallons? (around 3/4 of the res)
4) Is there any scientific evidence on what the best nutrients are to use? There's too much choice and too many opinions online. This suggests that there is no consensus, but I just want to be sure!
5) By my calculations, using Flora Duo in 16 gallons of water, I'd need about 2L of A and 4 litres of B - does this sound about right? That seems like an awful lot for one grow cycle, but it also seems correct.
6) Is 4 circulation fans overkill? I'm thinking of having 1 under the canopy, 2 blowing over the top and 1 more blowing towards the lights.

 

[Johiem]

Ok I'll weigh in.
1) every 7-10 days. I use smaller res's(5 gal) so it is easier for me to do an entire res swap.
2) I would reccomend a siphon of some kind, typical aquarium cleaner should work. But it will leave a bit at the bottom.
3) Your fill level will be determined by the depth of your net pots. You do not what your solution to touch the bottom of your nets, this can kill your girls. Ideally your solution should be about an inch(~2-3 cm)from the bottom of your net pot.
4) Nope. Nothing beyond anecdotal evidence. I'm happy with my GH trio. Also, I've not tried anything else.
5) couldn't truly tell you. By if you are mixing up 22 gal of solution you're going to need a lot of nutes.
6) In the beginning, yes. Massive overkill. Toward the end, not so much. Are you going to be in a tent? If so change one of those circulator fans into an inline extraction/exhaust fan.
Hope this helps.

 

[J232]

I'm in the middle of researching/buying everything I need for a DWC setup and just have some questions for things that are taking up lots of internet time researching.

1) How often do I need to change my reservoir water, assuming everything is going okay? (I know this is a topic of much debate)
2) How do I actually fill/change it? I have 2x84ltr(22 US Gallons) reservoirs (thought of using an auto siphon to empty and attaching a hosepipe to my shower hose) Because of electrics, I don't want to be carrying heavy water filled reservoirs in and out of my tent
3) Am I right in thinking that I would need to fill them up to about 16 US gallons? (around 3/4 of the res)
4) Is there any scientific evidence on what the best nutrients are to use? There's too much choice and too many opinions online. This suggests that there is no consensus, but I just want to be sure!
5) By my calculations, using Flora Duo in 16 gallons of water, I'd need about 2L of A and 4 litres of B - does this sound about right? That seems like an awful lot for one grow cycle, but it also seems correct.
6) Is 4 circulation fans overkill? I'm thinking of having 1 under the canopy, 2 blowing over the top and 1 more blowing towards the lights.

1- 10 days max, maybe more with 160L and good temps etc... variable depending on experience and conditions. Half change outs, stuff like that.
2- garden hose and sub pump or inline pump.
3- I would guess closer to half, 1.5-2” below the net pot, can be more later if you want.
4- no
5- sounds like a lot, i use less of gh flora line in 80 gallons. My cost was 3 gallons of nutes using the Lucas formula on a 4 month run, less res changes as well though.
6- depends on setup, don’t blow air at a DE bulb (if you are using one that is).

 

[J232]

Just saw that you are in buying build mode, what kind of space and what are you trying to achieve? How many plants and stuff like that. We can prob advise and help plan as well as answer questions.

 

[kernelforbin]

1) How often do I need to change my reservoir water, assuming everything is going okay?

For starting off, start by changing your res every 7 days. As you get more familiar with growing, you can start to "read" your plants by measuring pH, ppm, and notating the water level for changes. You'll start to get a sense for how quickly those nutrients are being used up, and adjust accordingly.

2) How do I actually fill/change it? I have 2x84ltr(22 US Gallons) reservoirs

In my setup using pumps for small buckets is more of a pain in the ass than it's worth. I just fill the new bucket up with water, mix in nutrients, and move the plant and airstone to the new bucket- removing the old one out of the tent. In your case you could make use of larger plastic drums to pre-mix your solution in, then use a small utility pump to actually pump the water out/in.

3) Am I right in thinking that I would need to fill them up to about 16 US gallons?

There is no rule on this. Different type of hydroponic setups use differing amounts of water. Generally speaking, you want to fill up the res in such a way that there is ~2 inch gap of air in between the bottom of the net pot and the top of the water. This isn't ironclad though... some hydro setups use a very tiny amount of water in the bottom of the res without issue. Water volume is not important.

4) Is there any scientific evidence on what the best nutrients are to use?

Yes... nutrients that contain nitrogen, potassium, and phosphorus. I'm being facetious. All nutrients contain the same basic building blocks in different amounts. Don't get bogged down in marketing nonsense. For a new grower starting hydroponics I would actually recommend a one-part nutrient solution for simplicity. I like the Flora series personally.

5) By my calculations, using Flora Duo in 16 gallons of water, I'd need about 2L of A and 4 litres of B

This seems excessive. Whether you have 100 PPM of nutrients present, or 1000 PPM, the point is that the nutrients are there in the first place. I'm also surprised a new grower is jumping into a 16 gallon system. I would start with 5 gallon buckets first because it gives you some margin of error.

6) Is 4 circulation fans overkill?

You certainly don't want gale force winds in there, but a nice breeze is healthy. Use your best judgement.

 

[bluegill]

When I swap res water for my 5g buckets, I place the plant with the bucket lid in a clean unused bucket and dump the water down the bathtub drain. I refill in the bathtub too. Then I put it back in the tent, add the plant and air assembly and dilute/add nutes the next day.

I usually do it every other week, and I top the water off in between. I just eyeball water level at this point because they drink it up quick.

 

[JP12345]

Thanks everyone for your replies. Very helpful.

@Johiem - I have a Phresh Hyperfan V2 already!

@J232 - 4x4 tent 4 plants. I've pretty much bought everything but the seeds and nutes.

@kernelforbin - Given that I need 2 inches of air, does that mean I should keep the plants out of the reservoir (and in the propagator) until their roots are long enough to be in the water? Re nutes - I've seen someone get great results with Flora Duo, but they're hard to source in my country. I've also heard positive things about Maxibloom, which are powdered I believe?