Reservoir change on seedlings & humic

Im about to transfer my seedlings to the main system and im thinking back to my lasts grows. The plants will be so small for the week or 2, and it seems like a gigantic waste tossing 8 or 9 gallons of water every 7 days when they will barely be drinking any. Does anyone let the res go 2 weeks on their first tank, and how do you handle feeding?

2nd question…im going to use General hydroponics Humic, silica, and for main nutrients FloraFlex full tilt schedule. Ive never used humic bevore, but from what im reading, it increases nutrient absorption to the point where you have to lower the dosage of nutrients. Does anyone use humic and have any advice on how much to cut back?


Lots of people go 2+ weeks without changing res. Just monitor your solution and adjust accordingly. You would just want to watch for large drops in ppm and ph swings. When you see either topping off res can get a little hairy because you’re not really sure what the reason for change is.


I’ve never used humic I use tribus grow, tribus bloom and fulvic acid for nutrient uptake. I cant see where lowering the nutrient level would have any benefit. That would result in less available food for the plants.

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Hey @ExoFly sounds like a good plan to me. I go two to three weeks before changing reservoir out completely. Definitely change when I flipped photoperiod to 12x12 and again 4 weeks into flower and then again 1 week before flush.

I am using the 10 part GH Flora pro feeding schedule.

I use Hydroguard each time I add or change my water to keep my root zone happy until the last three weeks before harvest.

GH Diamond Nectar is one of the additives I use for the Fulvic and Humic acid lacking in Hydroponic system. Which help transport nutrients up through the root system and throughout the plant.

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For the 2nd week do i just add in a full weeks worth of nutrients while topping the tank off?

I read that the increased nutrient uptake can burn them since theyre taking on more nutrients than once due to the acid. The person was saying the advantage is using less nutrients. You think i should go full bore?

I have 2 that are about a week behind…were still babies, so i only added in a 1/4 of the nutes it called for…theyre all doing well. The 2 in the back are starting to take off. 2 younger ones are just about settled in. However, i can tell im not pushing them as hard as i usually do. Still, impressed how big theyre getting on such little nutes.

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Do you just follow the feeding chart as if youre doing a res change? For instance, start of week 2 is upcoming, do i just add all of the nutes i would as if i was doing a clean res swap?

Also, do you still use full strength nutes with the diamond nectar. Thats whats im using too

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I think it depends on how ratio of res size to how much you’re adding and condition of plants. If you’re keeping up with topping off, plants are looking good, and ppm is stable i would say yes to using full strength nutrient solution for topping off with small amount. But you want to check your res first to see what’s going on. If you have a condition where you need to add 25% or more of res your res volume and ppm is climbing you may want to add reduced ppm solution or even straight water to get ppm back into range. This is one of those indicators that you may be going a little too long without a full replacement.


I agree with @dbrn32 balancing out the res could be tricky. When I run a res I only use 4-6gal at a time and change it out when I’m down to under a gal. Water evaporation would probably raise the ppms and fluctuate the ph I don’t think humic would make the plant take up more nutrients to where it would burn itself there only eating what is givin to them. Trying to balance out nutrients between plants that are in different growth stages that could be tricky that’s why I use Jacks321 nutrient program the mix is the same from seed to harvest (for the most part) I would try to feed according to the recommended ppm of what your nutrient program is calling for.


Ok thanks guys. Ill probably just try topping up this once and start doing weekly res changes again in week 3. I usually start with 8 gallons, but by end of veg theyre drinking so much i start doing 9 gallons. Its more like an aero/hydro setup. Res is in same tank as sprayers, so i need at least 3.5 gallons in at all times or the sprayer pump bottoms out. Sucks that i have to pump out 3.5 gallons of water every week and toss it, but better than me messing up the nutes :joy:

If i do a full res change in week 2, im throwing out like 6 gallons, which seems like a complete waste, so ill see how it goes waiting til week 3.

Appreciate all of your help.


I check the ppm and if it is inline with the same ppm then I’d go with that same ppm for the amount of water I’m adding.
I’m using individual 5 gallon buckets no res. So I just top off with the nutrients at the prescribed amount as indicated for that week of grow. If I notice tip burn or a need to adjust pH them I’ll just add water or/and the needed pH adjustments with.
DWC hydroponic plants can grow really fast. I’m using the following feeding schedule. I’m also using Hydroguard at the each watering up the final flush week.