Two ways that I have grown in the Bio-Buckets
- To do a grow without a reservoir change-out, requires mathematical skills and a great deal of knowledge of hydroponics solutions, but can be done if you calculate your reservoir correctly.
- This other way will probably render a more piece of mind for the beginner in the bio-buckets, water uptake based management determines the useful life to end at a point where the original volume has been completely replaced by plain water add backs. For example, when a 25 gallon reservoir has had 25 gallons of water added back to it. This is sometimes also referred to as the 100% add back point. As you add back plain water, simply make note of the quantity and replace the solution when the total quantity of all add backs equals the reservoir capacity. It should go without saying that I have tried both of these methods and there are very little deferent’s between them.
In case you haven't noticed, the determining factors behind a reservoir's useful life can all be traced back to the rate of water uptake, which is directly tied to the current demands of the crop. These demands will constantly increase as plants slowly fill their allotted space, often taking sixty or more days and spanning multiple growth stages before peak water uptake is eventually seen by the reservoir for the first time. As more water is being used by the plants, more nutrients are being removed from the nutrient solution, this naturally affects the nutrient balance in the remaining solution. In essence, the nutrient balance is also being controlled by the rate of water uptake. Simply put, a fuller garden space uses more nutrients because it uses more water. So what we have here is a direct relationship between solution volume maintenance (add backs) and pH/TDS maintenance. When that relationship is recognized, and this strategy enhanced to take advantage of it, additional gains in labor can be realized.
Reservoir Sizing, to buffer ph and nutrient uptake
An indoor home grower wanting a starting point for determining his reservoir size to go the entire grow start/finish, I have used this method with great success, here’s how I did it by approximately calculated 3 US Quart(s) or (2.839 liters) of reservoir water volume for each square foot of mature crop/bud canopy space.
This is not to say, the entire veg canopy space of your grow, only crop/bud space!! This is how I calculate my overall canopy space, which in my case 33sq feet times two is 66sq feet, this is a rule-of-thumb what I am about to say next, I dived that total number of 66sq feet into two, which is 33sq feet of mature crop/bud space, and if I use three quarts per crop/bud space, that equals out to be 24.75 gallons. My reservoir size is 25 gallons, this gives each sq-foot of mature canopy crop/bud space, three quarts per sq-foot. This water volume to space ratio has been found to produce both low maintenance and solution life expectancies that can easily coincide with growth stage nutrient formula changes. Waste not, want not:-)
Time Based---Management Strategy
The "replace it every week or two" idea is usually safe regarding plant health, however, it doesn't distinguish between those using small reservoirs with large crops and those using large reservoirs with small crops. What really determines solution life is the plants' ability to transpire, which is a function of its leaves. This means that if you have one more leaf today than you did yesterday, that today you would need a little more water than you did yesterday because of the new growth that was born since yesterday. As you can see, water uptake is a constantly moving target, and while it does have an element of time associated with it, it's really controlled by the mass of leaves in a garden at any given time.
To adopt a static time frame for when solutions should be replaced, doesn't account for the scant water uptake from the few leaves found on small seedlings/clones at the start of a crop, compared to the demanding water uptake of what those seedlings/clones will become after 60 days once they possess the thousands of leaves typical of some matured crops. Nor does it account for those gardens using a reservoir size that is undersized for the amount of growth it supports, while other gardens might be using oversized reservoirs. Someone using the "replace it every week or two" method with an undersized reservoir might be safe when a crop is new but not be as safe as he thought after the crop has matured, while someone using an oversized reservoir may be needlessly performing six or more solution changes over a twelve week crop when he could get the same results doing only three changes.
Clearly, time alone and your nutrient solutions useful life doesn't answer all the variables taking place between different grows or the growth stages those grows are in at any given time. In other words, this method is tied to the calendar, not to the plants. I suppose it should be mentioned that I have seen some fertilizer labels suggesting very strong mixes to be replaced at unusually frequent intervals for the strength of the mix. While it's unlikely that crop damage would result from following such instructions, one can only wonder if such labeling suggestions are an honest effort to simplify use of the product or to bolster sales for it, or both.
Enhanced Water Uptake Based Management
Formulating the starting solution mix in concert with the unique properties of your source water can allow you to run a nutrient solution without making any secondary pH/TDS correction adjustments during the entire life of that solution, thus limiting your maintenance to only the unavoidable plain water add backs. For example, an alkaline source water will tend to produce an alkaline solution as more and more of it is added back to the reservoir over time. You can avoid correcting unacceptably high pH levels later during a solutions' life by adjusting its starting pH a bit lower to compensate. Similarly, to keep the ending TDS of a solution from falling below the nominal threshold for a given crop, you can adjust the starting TDS a bit higher to compensate. The advantages of making all corrections at one sitting are obvious, and speaks strongly to the growers' economy of labor. It's not all that different from making the kids pee before they get in the car for that long drive!
BigTokes: "How-To" Of The Bio-Buckets 101
BigTokes: Hard-Core Bio-Buckets, First Big Run!!
BigTokes: Secound Big Run!!
BigTokes: AK-47 Plus H.D.F Bio-Bucket Style