I'm overwhelmed. Questions about Reservoir-/Nutrient-Management and how Plants take up Nutrients.

RookieMuffin said:

Ah ok I see that makes sense... they still use hydro sometimes but different style so they don't have to deal with changing res all the time.

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Nope_49595933949 said:

People absolutely change soil mid grow when they up pot.

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RookieMuffin said:

Do commercial grows do that to? They must have a very high bill when it comes to water and nutes if they change their million gallon reservoirs every week...?

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RookieMuffin said:

Hi hopefully someone can help and explain me some of my problems. I have some questions about how plants take up nutrients and how to manage the nutrient reservoir in different situations. I make a lot of research but sometimes it's to much different informations and it's hard to choose which one to trust. Maybe I think too complicated idk.

First of all... How do plants take up nutrients?

For example: If you have a res with EC 1.0 and the EC falls (plants eating more nutes than drinking water) or the EC rises (plants drinking more water than eating nutes) how to know which nutrients were eaten and which were not? Do they eat them in the same ratio they are present in the EC 1.0 water or do they take the ratio of nutrients them up how they need them?

Why I want to know this is because if they eat the ratio that is provided it's easier to manage the reservoir and not run into deficiencies. But if they it them at different ratios how they want it than it's a lot harder in my eyes because how do I know that there is not tooo much or too less of a specific nutrient if they eat their own ratio... that means one single nutrient could build up over time since they eat less of that nutrient compared to the others... What do you know about that problem? I don't want to get deficient plants just because one nutrient builds up overtime and I think the EC is right but the nutrient ratio was wrong because of the build up overtime... I also don't want to toss the whole res everytime and make a new one (because of cost of water and nutrients and so on).

Think about how commercial grows would do that? They don't toss their million gallon tanks always when something changes... they probably only add nutrients or water to get the desired EC.



Now the question about reservoir-/nutrient-management.

How would you manage your res taking into acount my question about nutrient ratios. Take into account that I use distilled water. I add Cal/Mag first to get water that comes close to tap water (but without all the other chemicals) and then I add my base nutrients to feed the plant.

Example 1 (Rising EC): Start res 10 gallon with EC 1.0

24 hours later the res is only 9 gallon and the EC has risen to for example 1.2

This means the plants drink more than they eat... So refilling the tank and lowering the EC is needed.

How would you do it in this Example 1? 1) fill it with distilled water back to 10 gal or 2) fill it with distilled water and Cal/Mag added to it to get back to 10 gallons

I don't want to add too much Cal/Mag over time maybe it builds up and one day I have maybe 90% cal/Mag and rest base nutrients and the plants start to become deficient. Do you see the problem I have with res management?



Example 2 (Lower EC): Start res 10 gallon with EC 1.0

24 hours later the res is only 9 gallon and the EC has lowered to for example 0.8

This means the plants eat more than they drink... So refilling the tank and raising the EC is needed.

How would you fill this? I would use 1) distilled water with cal/mag and a higher EC. or 2) fill with dist. Water with cal/Mag added and then later add the nutrients to the whole res to reach EC 1.0 again...

I think you get the problem I have... I don't really know how to manage my reservoir and I'm scared of nutrients that might build up over time. And I don't want to toss the whole reservoir everytime something is raising/falling... I'm a little overwhelmed with all the options I have. People who use only tap water and just one single nutrients it sounds easier because if EC rising fill with normal tap water (calmag already in) and if ec lowers will with tap and add nutes... I don't know how I should do it.

When I refill the res with only distilled water without cal/mag added then I might risk that one day I get a cal/mag deficiency... And if I refill with distilled water WITH Cal/Mag added to it I maybe rist that one day too much Cal/Mag is in the water if they don't take it up in the ratios it's already presend in the water...

Too much questions and too many variables for a beginner who don't want to make thinks wrong and loose their first grow. It is expensive and time consuming so loosing is not a good thing.

Maybe someone can help me out and shed some light on this topic or refer me to a lot of sources I can read which explains my problems further.

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FirstCavApache64 said:

I know that the ones I know change reservoir weekly but most of the guys I know that grow commercial do it in soil or Promix. Just my experience but I'm sure plenty do hydro. I also agree that while new it's best to try and keep things simple. A soil grow can help you learn more about the plant in my opinion as your not focused on the res, your watching the plant and environment. Lot's of people love hydro and grow killer plants with it, I just think it's something for growers with some experience.

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Redlig said:

From my experience... i usually change my rez about every 2 weeks sometimes sooner sometimes longer. I also top is off in-between changes with fresh water. The idea is not all nutrients get used in the same amounts. Also ph is a factor as well....so the way I see it I change my rez not because it's completely used but because some of the nutrients may be exhausted before others without you even knowing(unless your plant gives you signs) in my mind I change it before it is starving for a specific nutrient. Just don't overthink it I usually do around a quarter of what the bottle suggests ph between 5.5 and 6.2 and let er run. as I run them I may bump up to half strength but ever since I got the blue lab monitor I've realized most bottles are WAY off. You mix some of them the suggested amounts and I was getting damn near 3+ EC

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Dr.Dave56 said:

I used to grow in a 50/50 blend of Peat and Vermiculite and used GH liquid nutes - their 3 part Flora series.

I cut their recipes between 40% and 60%, watered every single day to runoff, measured that runoff and the pH like clockwork and never had a pblm, except for tip-burn which can be a sign of a well-done job. I fed nute levels apptopriate for the plants life-stages, early mid and late veg and the same with flower published online and the girls always thrived. I think they're right - don't overthink this. Good luck!!!

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xtsho said:

I ran recirculating hydro for years and never had any issues. I also used nothing but tap water, base nutrients, and bleach to keep things sterile. I changed out the reservoir every 10-14 days topping off with plain water in between. That's it. It's that simple.

The reason you're overwhelmed is because you're overthinking things which is common among the cannabis growing community.

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RookieMuffin said:

Thanks for the reply... I also think I'm overthinking a bit. Everywhere on earth are plants growing perfectly fine without someone measuring perfect nutrient ratios. It just works how it is... I'll slow down a little and try to stop overthinking things and keep it simple. No need to worry... I have a plant that grew in 2-3 weeks almost not at all due to problems with the nutrients strength and so on and it's still alive (and I think it's making a comeback right now). So looks like cannabis is hard to kill lol. Anyway... I still try to get her healthy before going into flower!

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rkymtnman said:

3 simple rules for hydro/DWC:


1. pH in range 5.5 to 6.1
2. don't overfeed
3. don't get root rot

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RookieMuffin said:

Yes I think so too... now... since there are a lot more variables to keep in check... soil is much easier. But since I'm already growing I think I have to grind thru and make this happen somehow lol

One day I want to grow both... soil and hydro but right now I'm too deep in... I can't go back right now lol. Hope this grow goes well! But here are a lot of nice people who help real good and I needed that already but as I said a lot of nice folks with a lot of experience who help to grind thru things.


Ok my bottle recommendation is pretty accurate but I think I still have to lower the feeding especially in the beginning... Otherwise I'm feeding a seedling with 1.2 EC or something like that lol... One day when I've more experience I can experiment with different feeding amounts but right now I try to stay safe and do what people tell me over here and monitor my reservoir and go by that. My EC meter sucks one day I need 1ml and the other day I need 0.5ml to get the same EC which doesn't make sense so I think it's time for a new EC meter since this shit thing is broken... Another way to kill your plants if your instruments fail... The ph meter is probably off too so yeah time for a new one!


Thanks for the reply. I also use the GH 3 part flora series! Right now I have a plant with about 5 nodes... I feed at 60% of recommended dose BUT I think the EC raises over time so maybe 60% is a bit too much right now... What do you think? What would you feed a plant that is about 4 weeks old and has about 5 nodes? (o maybe it's early veg?? idk in what stage I am!) In my other thread you can see a picture if you need one to estimate the size and the amount to feed but the plants are deficient lately but they come back to live right now I think.

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amneziaHaze said:

I think she eats all she can handle.if she picked she wouldnt burn.soo you have to balance your nutes.one hydro grow i would top off with 1l nutrients daily and it was the best grow i had

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Dr.Dave56 said:

My personal observations about cannabis stages:
Seed to seedling - 4 days
Seedling to early veg - 11 to12 days
Mid veg - 2 to 4 weeks
Late veg - 4 to 8 weeks
Now I'm only vegging for 5 weeks, so the guidance above changes a bit.

I recommend that you do a flush if you haven't done so already and then switch to using only 45% of the recipe on their bottles. Watch your girls for a few days and see how they're reacting. I also highly recommend the use of PK13/14 by Canna or GH's Liquid KoolBloom, 0,10,10 in flower. Cut their recipe to 50% in early flower and by late flower follow the recommended recipe. Keep an extra EC and pH meter around and be sure to calibrate them as needed. Good luck!!

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RookieMuffin said:

What do you guys say about increasing the light intensity and finding the sweet spot? Over the course of some days/weeks increasing the light until EC lowers all the time or they show signs of light stress? I think my plants could handle more light by now... they are basically still under seedling strength. I want to increase it but I don't want to increase it by a lot in about a day not that I overdo it and they suffer...

What would you do? How much do you think they can handle? They are 4 Weeks old.

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Dr.Dave56 said:

Dr. Bruce Bugbee and Sean over at Migro discuss optimum light intensity for cannabis in terms of PAR and micromols/second. You'll need a quantum meter to measure the PAR that you're giving your girls. If you have a lux meter, you can convert that to a PAR # +/-.

Veg is like 250-600 umols/sec, early flower - 601-750 umols/sec, late flower is 751-1600 umols/sec.

I push 650 umols in veg, to 750 at the flip and an average of 800 to 1,200 across the entire canopy for the duration through harvest.

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bk78 said:

Oh god enough with the bugbee stuff. And Shane doesn’t even grow weed.

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Dr.Dave56 said:

Not liking it? Don't read it. Bugbee is my growmee.

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