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How can I properly maintain my hydroponic nutrient solution?

Smokin Moose

Fallen Cannabis Warrior
Reservoir maintenance is the routine task of keeping the hydroponic nutrient solution in the reservoir from becoming too strong or toxic as the water is being evaporated and the nutrients within the solution are taken up by the plants.

Simply put...
Top off daily with *half strength nutrients, alternating days topping up with plain water. Change the entire reservoir with fresh solution every ten days to two weeks. (*half the strength of your current new reservior starting strength)

Why should you?
One problem in hydroponics solution maintenance, as water is being taken up by the plants as well as evaporating out of the solution, the concentration of nutrient salts in the solution becomes gradually stronger, sometimes to the point of certain elements becoming toxic to the plants. The TDS will always become stronger as water is taken away from the solution.

Another problem, is that hydroponically grown plants will take up what they need as they need it from the nute solution. A nutrient solution left alone will end up lacking key nutrients, with a build-up of *toxic levels of other key nutrients. *Toxic in the solution, as well as in the plants.

The only way around these problems for the average hydroponic grower, is to practice sound reservoir topping off procedures. The most widely accepted maintenance method, involves daily topping off and routine reservoir solution replacement. IE: Topping off the reservoir daily with a nutrient solution which is half of the current new reservoir strength, alternating days by topping off with plain water and finally, changing the entire res solution at least every two weeks.

Changing the reservoir solution every two weeks, will give the plants a fresh and well balanced nute mix, which has not been altered by the plants nutrient uptake.

*Many scientific studies have been performed, which demonstrate these facts by GCMS testing of the nutrient solution contents and the nutrient salts contained within the actual plant tissues, as the plants "take-up" the specific nutrients in the solution.

Metaphorically speaking...
Plants will take up excessive levels of some nutrients, leaving the solution lacking in certain key nutrients. Just like a puppy would make him/her self sick if it were allowed to feed from a bottomless food bowl, plants grown hydroponically can harm themselves with nutrient deficiencies, lockouts and overdoses, if allowed to continue feeding without some control over whats available in the "food bowl".


New Member
The simplest way to eliminate evaporation is to keep the rez cool. If you have a lot of lamp heat, move your rez to a cooler place, even outside the room. My rez is 5G. I put jugs of ice in the rez. These virtually eliminates evaporation

As to topping off, if you D2W you never have to worry; simply make up enough nutrient to last for 4-5 days, as rez goes down, simply top off

Of course this only works if you are using F&D type method where your runoff is minimal: In my HPA hybrid X with F & D, I go through ~ one gallon per 24 hours.



New Member
After reading all this information, I’ve got enough information on running a hydroponic system. All successful growers know how to keep nutrient solution strength ideal. The best way is to get an electrical conductivity (EC) meter. This device helps you find out how strong or weak your nutrient solution is.

When it comes to maintaining your nutrient solution, it is important to check both the strength and pH levels at least twice a day. Regardless of the size of the reservoir, you can take a sample of the water in the medium and mix a few drops of your pH indicator. On shaking the mix up, you’ll get to know the current pH level!
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