Adjusting nutes in rdwc system

420Mn · Jun 22, 2023

Looking for advice on how to adjust nutrient strength weekly in a rdwc system without doing a water change.

Example: Week 1 use 1/4 tsp per gallon of each nutrient solution. Week 2 use 1/2 tsp per gallon.

Does this mean for week 2 I would add another 1/2 tsp per gallon to system? And if so, can I slowly add nutrient solution to the system while its circulating? The GH flora series instructions say do not pre mix, add to water only. Does that just mean dont mix the solutions together or does it mean dont pre mix nutrient water, add nutrients to the system instead?

Im aware I will need to do a complete water change when transitioning to bloom and when flushing at the end.

Drop That Sound · Jun 22, 2023

Always follow the directions, and mix the nutrient parts in the right order when called for. One at a time, mixing each time separately.. don't add them to the water all at once is basically what they mean, or it will cause a reaction and cause some components to precipitate and "fall out". Use your Si supplements first if using it.

Also, its always advisable to mix a little water into your PH solution, instead of adding the concentrated drops directly to the res all at once. You can use the system to mix the nutes though, just make sure to wait long enough that each part gets thoroughly mixed before adding the next. Not really the best way to do it, but will work.

Get a TDS meter so you can keep an eye on your EC/PPM levels too. By keeping track of the water level, the EC\ppm, and the PH, you can calculate exactly what they need most the time just by those 3 factors alone..

420Mn · Jun 22, 2023

Drop That Sound said:
Always follow the directions, and mix the nutrient parts in the right order when called for. One at a time, mixing each time separately.. don't add them to the water all at once is basically what they mean, or it will cause a reaction and cause some components to precipitate and "fall out". Use your Si supplements first if using it.

Also, its always advisable to mix a little water into your PH solution, instead of adding the concentrated drops directly to the res all at once. You can use the system to mix the nutes though, just make sure to wait long enough that each part gets thoroughly mixed before adding the next. Not really the best way to do it, but will work.

Get a TDS meter so you can keep an eye on your EC/PPM levels too. By keeping track of the water level, the EC\ppm, and the PH, you can calculate exactly what they need most the time just by those 3 factors alone..

Thanks man! I do have an ec/ppm meter arriving tomorrow. If mixing nutes in the system isn't the best way to do it, is there a better way you would advise me to follow? One that doesn't involved a complete water change?

Drop That Sound · Jun 22, 2023

I like doing partial res changes now days. I feel its a good middle ground between keeping it clean, but not wasting too much water and nutrients. I've done full grows without doing a single res change before (big res though), and nothing but add backs, just curious how it would work out, andf it was fine, lol.

420Mn · Jun 22, 2023

Drop That Sound said:
I like doing partial res changes now days. I feel its a good middle ground between keeping it clean, but not wasting too much water and nutrients. I've done full grows without doing a single res change before (big res though), and nothing but add backs, just curious how it would work out, andf it was fine, lol.

The nutrients come with a nutrient schedule (micro, grow, and bloom) that's broken down in weeks, based on the stage of growth. Is that how much to add weekly if not doing a water change?

Drop That Sound · Jun 22, 2023

420Mn said:
Thanks man! I do have an ec/ppm meter arriving tomorrow. If mixing nutes in the system isn't the best way to do it, is there a better way you would advise me to follow? One that doesn't involved a complete water change?

If anything, just dilute the parts a little bit before adding to the system each time. Use a smaller jug\bucket or whatever. You could scoop some water right out of the res with the jug, add it, and pour back in, etc. Or use fresh water if needed. Mixing in the system kind of is the only way to mix if not doing full res changes. Unless you figure out to add a top up/addback res with a float valve, or implement a sophisticated dosing setup that replenishes the solution in a more controlled and timely manner..

sandman83 · Jun 22, 2023

buy a rubbermaid or husky trash can, mix the extra solution you want to add to proper ppm, add to tank. If you want to top off with nutrient solution during the week, use it from this and keep aerated.

Changing the solution from "week 1" to "week 2" schedule for me has always involved changing the tank out but I run a much smaller system for veg so its a few gallons NBD.

Drop That Sound · Jun 22, 2023

420Mn said:
The nutrients come with a nutrient schedule (micro, grow, and bloom) that's broken down in weeks, based on the stage of growth. Is that how much to add weekly if not doing a water change?

No thats just a general feeding guideline, and does consider you would be doing full changes each week. If you kept adding, your EC would just keep going up if the plants arent consuming that much. They will have different needs at different stages of growth. Your feeding chart should be reading the plants and the res, and keeping the proper levels in check. You might be barely adding anything the first few weeks, or even month with a large system and small plants..

420Mn · Jun 22, 2023

sandman83 said:
buy a rubbermaid or husky trash can, mix the extra solution you want to add to proper ppm, add to tank. If you want to top off with nutrient solution during the week, use it from this and keep aerated.

Changing the solution from "week 1" to "week 2" schedule for me has always involved changing the tank out but I run a much smaller system for veg so its a few gallons NBD.

Thank you!

Drop That Sound · Jun 22, 2023

Drop That Sound · Jun 22, 2023

You definitely wanna be prepared to do a full res change, even if you don't plan on it, so yea it helps to have extra barrels/containers/buckets..

Drop That Sound · Jun 22, 2023

You'll likely end up needing way less btw, which is usually more with DWC. I run small plants around 300 ppm, veg at 5-600 (even huge trees), and never go over 1000 or 2.0 ec in flower. Usually not over 7-800 for most strains I feed based off charts like the ones above, and let plants tell me what they want, but still use the proper ratios.

420Mn · Jun 22, 2023

Drop That Sound said:
No thats just a general feeding guideline, and does consider you would be doing full changes each week. If you kept adding, your EC would just keep going up if the plants arent consuming that much. They will have different needs at different stages of growth. Your feeding chart should be reading the plants and the res, and keeping the proper levels in check. You might be barely adding anything the first few weeks, or even month with a large system and small plants..

I just don't understand how to keep the proper levels based on the different stages of growth without doing a complete water change. Ec/tds doesn't calculate how much of each, micro, grow, bloom or calmag is in the system. Say week 4 advises 1tsp per gallon of something and week 5 only advises 1/2, or vice-versa, how does a person account for that without a water change. How does a person judge whether the system needs more or less of each nutrient?

Drop That Sound · Jun 22, 2023

Thats because you can't really. IME with DWC its not that important though. You could keep adding the same mix of the GH trio all the way through, just changing the overall strength, and still grow nice plants IMO. Some of my best DWC grows ever were using 1 part bloom formulas the whole way for example. Just keep the levels in check like those charts I listed above direct you, and the plant will pretty much take what it needs. . Maybe phase out of the grow part later towards the end.. Throw in a few partial res changes for piece of mind, and If you need to change the res like it says, do it.

I been using salts the last few years and saving a lot of money so I change out more often, but i was experimenting with not changing the res before that trying to conserve what i had, and had a few good runs, as good as any. Like i said i was running larger system though, with like 80 gallons.

420Mn · Jun 22, 2023

Drop That Sound said:
Thats because you can't really. IME with DWC its not that important though. You could keep adding the same mix of the GH trio all the way through, just changing the overall strength, and still grow nice plants IMO. Some of my best DWC grows ever were using 1 part bloom formulas the whole way for example. Just keep the levels in check like those charts I listed above direct you, and the plant will pretty much take what it needs. . Maybe phase out of the grow part later towards the end.. Throw in a few partial res changes for piece of mind, and If you need to change the res like it says, do it.

I been using salts the last few years and saving a lot of money so I change out more often, but i was experimenting with not changing the res before that trying to conserve what i had, and had a few good runs, as good as any. Like i said i was running larger system though, with like 80 gallons.

Now i think I'm understanding. The nutrient ratios don't need to be perfect provided I stay within the proper ec/ppm range as the plants will only consume what they need of each nutrient. Throw in a water change here and there when transitioning to get things on par with that specific growth phase or when the above chart advises to do so, and then follow the chart.

sandman83 · Jun 22, 2023

420Mn said:
Now i think I'm understanding. The nutrient ratios don't need to be perfect provided I stay within the proper ec/ppm range as the plants will only consume what they need of each nutrient. Throw in a water change here and there when transitioning to get things on par with that specific growth phase or when the above chart advises to do so, and then follow the chart.

Correct, following the weekly charts per manufacturer on the "lighter side". They will recommend dumping/cleaning the reservoir every 7-14 days as well. To me its easier to just topoff the tank with plain tap water ph to 5.8 until I've replaced 50% of the water in the tank again. Then dump and refill, ends up being about a week for my system.

I'm probably guilty of dumping more than I need to but its easier to stay within range and keep the slime at bay.

420Mn · Jun 22, 2023

sandman83 said:
Correct, following the weekly charts per manufacturer on the "lighter side". They will recommend dumping/cleaning the reservoir every 7-14 days as well. To me its easier to just topoff the tank with plain tap water ph to 5.8 until I've replaced 50% of the water in the tank again. Then dump and refill, ends up being about a week for my system.

I'm probably guilty of dumping more than I need to but its easier to stay within range and keep the slime at bay.

Thanks man, I appreciate all your assistance! I wish I could change it out every week or two but my system consists of 5 12g totes and it seems incredibly wasteful to dump that much water and nutes so frequently. Thanks again man, you've been a huge help

Drop That Sound · Jun 22, 2023

If going with minimal res changes, go minimal with what you feed too. As in, just stick with the base nutrients only. Don't dump in anything like additives\acids\silicates\boosters or anything that could funk up your res & throw it out of whack in anyway. Keep it sterile, and the water cool if possible. Run some pool shock granules or bleach every once in awhile at low ppms.

420Mn · Jun 22, 2023

Drop That Sound said:
If going with minimal res changes, go minimal with what you feed too. As in, just stick with the base nutrients only. Don't dump in anything like additives\acids\silicates\boosters or anything that could funk up your res & throw it out of whack in anyway. Keep it sterile, and the water cool if possible. Run some pool shock granules or bleach every once in awhile at low ppms.

Only thing extra I intended to add was either medical grade h202, pool shock, or southern ag garden friendly fungicide. Leaning towards pool shock as it's so inexpensive. Also intend to start with half the recommended dose of the GH trio. Should I also half the dose of calmag alongside the nutrients?

Drop That Sound · Jun 22, 2023

I wouldn't even use the calmag unless you need it for some reason.. Can't hurt though I suppose.. Ya pool shock is cheap, and last a long time.

Try it half strength and see where you end up, and go from there. I would probably go 1/4 to start small plants though.

Adjusting nutes in rdwc system

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