Topping up the reservoir with a mixed nute solution

Oh So Grow So · 08-20-2008, 04:40 PM

Ok this may seem a like a basic do or dont but I think its more complicated than that. If you grow in a 5 gallon or smaller DWC reservoir you have to top up the solution through out each flowering week. So you have to add water or the plant will drink it self out of house and home. The dilema is, if you add just straight water you're diluting the solution making it too weak for the plant. But the plant takes up nutrients at different levels, so just mixing up the same nute solution you originally made at the beginning of the week isn't exactly a great solution because there will be some nutrients with excessive levels and some that are at insufficient levels.

What's the answer here?

Oh So Grow So · 08-20-2008, 10:33 PM

alright GD2K and the rest of you hydro guru's where you at?

BigTigga · 08-20-2008, 10:37 PM

Im with you on this one brother. Im going to be doing a DWC in huge 50 gal rubber maid tubs and also want to top off my res but not diluting it as well.

let us both pray

boss429 · 08-20-2008, 11:14 PM

i'm no guru but i'd use a TDS (total disolved solids) meter. use two containers of water; one would be the nutrients in the right ratio but highly concentrated and the other one would be plain filtered water.
i would get the resevoir close to full with plain water then use the concentrated solution to get the PPM to where i like it.
you still need to throw the water out and start over every ten to fourteen days or so.

Oh So Grow So · 08-20-2008, 11:21 PM

Yeah, that doesn't quite address the dilema though.

If you top up the solution with any nutrients at all after the plants have consumed a good amount of water, you're risking putting the nute ratios out of balance. Because they dont consume all nutrients at a uniform rate. So even if you add your original ratio at say 1200ppms and they consumed an equal amount of water as they did nutrients, they still could have consumed a whole lot of N but but not as much P or K (or any of the other essential elements) then you're heavy in P K and light in N.

As of right now, that's what I'm doing. Because I know that just diluting the water down to 400ppms is worse for the plant than throwing the nute ratios out of balance. I also know this isn't what's best for it.

boss429 · 08-20-2008, 11:40 PM

there's no way you can know the ratio the nutrients are being consumed in. but you can be sure that the balance is close enough to what they need for about 10-14 days after you mix it, so at that point throw it out.
i thought you were referring to how to keep the ppm stable throughout that two week peroid...this is the technique i use i'm sure people have other ones.

BigTigga · 08-21-2008, 01:43 AM

we gotz to bwain storm here guys. The nute solution must not be smarter then us!!!!!!!!!!!!!!!!!!!!!!!!

knna · 08-21-2008, 06:47 AM

In order to deal with this issue, i like to think that nutes added are either already in the plant, or still in the res. That way you can think on total nutes added along all the cycle.

When refilling, the best is to refill in a way you set nutes concentration at the best level. The baseline is the previous EC/ppm level used. If ppm has ramain stable ir mean plants is uptaking similar amount of water and nutes, so you must refill using the same concentration on the refilling. If ppm went up, use a lower concentration, and if it went down, use higher concentration.

Some people like to use a higher concentration on a refill and just use plain water on the next refill. It work fine too and its easier as you need to prepare NS less often, but it does more difficult to track the optimun ppm level: the starting concentration may take into account the next refilling to know the average EC/ppm. But i prefer to keep EC as stable as possible.

In a hurry, you can refill with plain water if it dont drop EC level too much, and compensate it on the next refill. But i would advice to refill always with a NS with a concentration adapted to what happened before. It provides the plants the more stable environment and allows to notice fast any sudden change. Its not strickly required, but is a good rule of thumb.

knna

**GreenDragon2k** · 08-21-2008, 06:56 AM

Quote:

Originally Posted by Oh So Grow So

What's the answer here?

Thats the entire reason for a reservoir changes really... Not much you can do but change your reservoir out completely once every 7-14 days so you know the plants have the proper nutrient levels.

Soon as you have topped up in equal volume of your reservoir, you'll want to think about doing a water change. Thats the generally accepted point as when things have gotten too far out of whack to try and adjust so you just start fresh.

Oh So Grow So · 08-21-2008, 08:47 AM

great. so I have been doing what should be done

yeah I'd say big mama goes through about 5 gallons a week

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