RNC and TDS Explained, OR Topping Off the Reservoir
Topping Off the Tank's Reservoir in DWC and many Small Hydro Systems. This does not apply to VERY LARGE systems.
Something sort of technical needs explaining that I'd like to attempt to explain. I really do own 14 books on Hydroponics and Indoor Growing. And I have studied them too. Some of the books were written simply, and some are difficult for me to comprehend and even more difficult for me to explain. (I'm an OLD Stoner) The books all vary a little on the perfect pH level, and they all vary on LIGHTING, some books were written way before CFLs were sold, or when CFLs were new on the scene. But they all agree on Topping Off the Tank and Draining and Replenishing the water and nutrients in a DWC reservoir.
You will need to read both explanations, the RNC and the TDS. I've tried to simplify it.
After the nutes are added to the tank and the pH is balanced, the plants start eating, consuming the food. Logically, the larger the tank, the more water there is, and the more nutes you need. Logically, the larger the plants, the more they will eat from the tank. Logically, the more plants that are in the tank, the more they will eat. And logically, the more they eat, the more nutes that you need in the tank. The amount of nutes provided is in relationship to the amount of water, NOT the amount of plants. It is the Ratio or Proportion in the water that is important. The amount of nutes added to the tank are measured by we commonly call a PPM Meter, PPM meaning parts per million.
The Instructions on the nutrients contain the proper amount of nutes to add to the water, usually determined by "per gallon", and not by "per plant" or "size of plants". In the beginning, we start with 1/4 or smaller dose of nutrients, because a full dose is meant for full grown plants. If we use a ppm meter, we seek a ppm of 150 to 250 ppms above the ppm of the water, on average for small young sprouts and seedlings, it varies from nutrient to nutrient. As the plants grow, we then slowly and gradually increase the nutrients fed to them, and consequently we increase the ppm. By the time the plants are over a foot tall, we will be in the neighborhood of a ppm of 600, then 800 on up to 1200 ppm or higher. Some growers risk even higher ppms, watching the leaves tips for yellowing, to know when to back off with feedings. And as we add more food, the plants grow and eat more, indicated by them also drinking more water. As a rule of thumb, we figure if they drank half of the water, they then must of ate half the food. That is close to being right, but not precisely. If the grow room was exceptionly HOT, they can drink more water without eating more food. And consequently, some days, they eat more, some days they eat less, regardless of the amount of the water missing.
As they eat, they do not eat all of the delivered nutes at the same rate, or same proportion, and that changes the pH and the ppm. It also changes what they call the RNC, or RELATIONSHIP OF NUTRIENT CONCENTRATION. That CHANGE is not easy to calculate or measure, like the ppm or pH is easy to measure.
When the proper amount of nutrients are first introduced or added, the RNC is perfect, or properly proportioned. In other words, there are specific amounts or precise amounts of each needed nutrient. The exact amount of needed Nitrogen, Phosphorous, and Potash, also commonly called Potassium are present and available for food for the plants in the beginning.
BUT, as the plants eat, they do not eat all of the nutrients in a perfect proportion or at a perfect rate or equal rate. Some days, they want what grows longer roots, some days, they want what makes more leaves. The plants actually nibble at some nutrients in the mix each day, and gobble down some others. Some of the nutrients are not hardly eaten at all, some are absorbed very quickly. This creates an IMBALANCE of the mix. If you add more water and nutes daily to replace the eaten nutes, (CALLED TOPPING OFF) the IMBALANCE INCREASES. If you only add plain water daily, again, Top It Off, you still get the imbalance. AND the nutes not eaten, or the nutes that are increased daily cause a build up of nutes, and that creates a BAD imbalance of the RNC.
When this happens, the imbalance, the water becomes TOXIC and unusable even tho the ppm meter says there is a proper amount of nutrients. The plants say I AM NOT HAPPY WITH THE BUFFET and like a spoiled child unhappy at the dinner table, they suddenly refuse to eat anything. This is called NUTRITIONAL LOCKOUT. This happens even tho the ppm meter says there are plenty of parts per million of nutes in the water. The ppm meter does not indicate if the nutrients are balanced or at a toxic level. It just indicates there is plenty of food on the table.
AND
Daily Maintenance of the DWC reservoir is mostly keeping the pH at the proper level, and keeping the same level of water in the tank as it is used or evaporates. It is also keeping the nutrient mix or nutrient solution at a proper level, a level that is NOT toxic or too strong.
In the day to day course of maintaining the tank two problems occur. Remember how we discussed ppm, parts per million? Then we discussed RNC, RELATIONSHIP OF NUTRIENT CONCENTRATION. Well, we also need to discuss TDS, Total Disolved Solids. (Some books say Total Disolved Solids, Some Books use Total Disolved Salts, for some reason unknown to me)
As the water evaporates or is consumed, the concentration of TDS becomes stronger, to the point of being Toxic. The TDS increase as the amount of water decreases. This creates the need to replenish the water, to replace the water, or to "top off". As we replace that missing water, we create an IMBALANCE. Hydroponic grown plants eat what they need, as they need it, and they leave some nutes to build up and accumalate into a posionious or toxic level.
This creates the need to daily TOP IT OFF. (to put a cut on it) Feedings and Draining and Replenishing is simple enough, daily replace what you estimate is gone, consumed, eaten, and absorbed.
But weekly, you need to clear the buffet table and start all over with fresh foods and quit serving left-overs. This gives the plant not only a well balanced buffet table to eat from, but also supplies it with FRESH Food that has not been altered by the plants being picky and choosey.
And, there is the Growth Spurt you will get during the Drain, as the roots get a 5 to 15 mintues air bath. It also gives you the opportunity to look for crimped air hoses, scrub the air stones clean and look for debris and trash in the tank that messes with the pH balance.
Also, as the water ages, undesirable harmful microbes appear and grow in the water. You also take the chance of insect larvae and algae appearing, and weekly draining the tank helps prevent those problems too.
THIS IS WHY WE MUST WEEKLY DUMP IT ALL AND START ALL OVER.
THIS IS WHY WE MUST DRAIN AND REPLENISH WEEKLY, regardless of whether we TOP OFF with plain water, or TOP OFF with water and a fractional dose of nutes.
Changing the water weekly maintains the proper RNC and the proper TDS.
Again, this does not apply to the Ebb and Flow systems or very large 55 gallon reservoir systems, or organic nutes systems, or systems that you are trying to maintain a micro organism-enzyme balanced system.
Topping Off the Tank's Reservoir in DWC and many Small Hydro Systems. This does not apply to VERY LARGE systems.
Something sort of technical needs explaining that I'd like to attempt to explain. I really do own 14 books on Hydroponics and Indoor Growing. And I have studied them too. Some of the books were written simply, and some are difficult for me to comprehend and even more difficult for me to explain. (I'm an OLD Stoner) The books all vary a little on the perfect pH level, and they all vary on LIGHTING, some books were written way before CFLs were sold, or when CFLs were new on the scene. But they all agree on Topping Off the Tank and Draining and Replenishing the water and nutrients in a DWC reservoir.
You will need to read both explanations, the RNC and the TDS. I've tried to simplify it.
After the nutes are added to the tank and the pH is balanced, the plants start eating, consuming the food. Logically, the larger the tank, the more water there is, and the more nutes you need. Logically, the larger the plants, the more they will eat from the tank. Logically, the more plants that are in the tank, the more they will eat. And logically, the more they eat, the more nutes that you need in the tank. The amount of nutes provided is in relationship to the amount of water, NOT the amount of plants. It is the Ratio or Proportion in the water that is important. The amount of nutes added to the tank are measured by we commonly call a PPM Meter, PPM meaning parts per million.
The Instructions on the nutrients contain the proper amount of nutes to add to the water, usually determined by "per gallon", and not by "per plant" or "size of plants". In the beginning, we start with 1/4 or smaller dose of nutrients, because a full dose is meant for full grown plants. If we use a ppm meter, we seek a ppm of 150 to 250 ppms above the ppm of the water, on average for small young sprouts and seedlings, it varies from nutrient to nutrient. As the plants grow, we then slowly and gradually increase the nutrients fed to them, and consequently we increase the ppm. By the time the plants are over a foot tall, we will be in the neighborhood of a ppm of 600, then 800 on up to 1200 ppm or higher. Some growers risk even higher ppms, watching the leaves tips for yellowing, to know when to back off with feedings. And as we add more food, the plants grow and eat more, indicated by them also drinking more water. As a rule of thumb, we figure if they drank half of the water, they then must of ate half the food. That is close to being right, but not precisely. If the grow room was exceptionly HOT, they can drink more water without eating more food. And consequently, some days, they eat more, some days they eat less, regardless of the amount of the water missing.
As they eat, they do not eat all of the delivered nutes at the same rate, or same proportion, and that changes the pH and the ppm. It also changes what they call the RNC, or RELATIONSHIP OF NUTRIENT CONCENTRATION. That CHANGE is not easy to calculate or measure, like the ppm or pH is easy to measure.
When the proper amount of nutrients are first introduced or added, the RNC is perfect, or properly proportioned. In other words, there are specific amounts or precise amounts of each needed nutrient. The exact amount of needed Nitrogen, Phosphorous, and Potash, also commonly called Potassium are present and available for food for the plants in the beginning.
BUT, as the plants eat, they do not eat all of the nutrients in a perfect proportion or at a perfect rate or equal rate. Some days, they want what grows longer roots, some days, they want what makes more leaves. The plants actually nibble at some nutrients in the mix each day, and gobble down some others. Some of the nutrients are not hardly eaten at all, some are absorbed very quickly. This creates an IMBALANCE of the mix. If you add more water and nutes daily to replace the eaten nutes, (CALLED TOPPING OFF) the IMBALANCE INCREASES. If you only add plain water daily, again, Top It Off, you still get the imbalance. AND the nutes not eaten, or the nutes that are increased daily cause a build up of nutes, and that creates a BAD imbalance of the RNC.
When this happens, the imbalance, the water becomes TOXIC and unusable even tho the ppm meter says there is a proper amount of nutrients. The plants say I AM NOT HAPPY WITH THE BUFFET and like a spoiled child unhappy at the dinner table, they suddenly refuse to eat anything. This is called NUTRITIONAL LOCKOUT. This happens even tho the ppm meter says there are plenty of parts per million of nutes in the water. The ppm meter does not indicate if the nutrients are balanced or at a toxic level. It just indicates there is plenty of food on the table.
AND
Daily Maintenance of the DWC reservoir is mostly keeping the pH at the proper level, and keeping the same level of water in the tank as it is used or evaporates. It is also keeping the nutrient mix or nutrient solution at a proper level, a level that is NOT toxic or too strong.
In the day to day course of maintaining the tank two problems occur. Remember how we discussed ppm, parts per million? Then we discussed RNC, RELATIONSHIP OF NUTRIENT CONCENTRATION. Well, we also need to discuss TDS, Total Disolved Solids. (Some books say Total Disolved Solids, Some Books use Total Disolved Salts, for some reason unknown to me)
As the water evaporates or is consumed, the concentration of TDS becomes stronger, to the point of being Toxic. The TDS increase as the amount of water decreases. This creates the need to replenish the water, to replace the water, or to "top off". As we replace that missing water, we create an IMBALANCE. Hydroponic grown plants eat what they need, as they need it, and they leave some nutes to build up and accumalate into a posionious or toxic level.
This creates the need to daily TOP IT OFF. (to put a cut on it) Feedings and Draining and Replenishing is simple enough, daily replace what you estimate is gone, consumed, eaten, and absorbed.
But weekly, you need to clear the buffet table and start all over with fresh foods and quit serving left-overs. This gives the plant not only a well balanced buffet table to eat from, but also supplies it with FRESH Food that has not been altered by the plants being picky and choosey.
And, there is the Growth Spurt you will get during the Drain, as the roots get a 5 to 15 mintues air bath. It also gives you the opportunity to look for crimped air hoses, scrub the air stones clean and look for debris and trash in the tank that messes with the pH balance.
Also, as the water ages, undesirable harmful microbes appear and grow in the water. You also take the chance of insect larvae and algae appearing, and weekly draining the tank helps prevent those problems too.
THIS IS WHY WE MUST WEEKLY DUMP IT ALL AND START ALL OVER.
THIS IS WHY WE MUST DRAIN AND REPLENISH WEEKLY, regardless of whether we TOP OFF with plain water, or TOP OFF with water and a fractional dose of nutes.
Changing the water weekly maintains the proper RNC and the proper TDS.
Again, this does not apply to the Ebb and Flow systems or very large 55 gallon reservoir systems, or organic nutes systems, or systems that you are trying to maintain a micro organism-enzyme balanced system.
counter acting an infestation of mites. Consequently the clone (in the 5 gl pail) and one of the plants in my cooler were dwarfed by the survivor of MiteGate. In fact the clone and the replacement were growing at the same rate and were the same size. This led me to transplant MiteGate survivor to the pail and the clone to the cooler. Now MiteGate survivor is approx. 26" tall while the cooler plants are at 10". MiteGate being at one end of my tent and the cooler at the other makes daily maintenance less restrictive and seems not to have had any deliterious effect on the plants. In the pail I have a 6" Oxystone on a single outlet pump. The root ball on Mitegate is beautiful. The seedling has well established roots (water pump hose removed) and the clone's roots are just establishing themselves in the water. (water pump hose still in place.) The water in both tanks smells sweet (last rez change 7 days ago today 7/17/10) is clear and free from debris. I'm using Nutrafield A & B only. PH balance is maintained daily, if required. I'll never know if more frequent rez changes would have been more productive. Undoubtedly they would have been. I'm thinking about doing another change right now. That's a lot of work. I'll let you know.
Damn rose as always a joy to read from my 1st (of many mentors) I've got this book marked. I've got a few more threads I wana keep handy as well. You can blame my past absence on this 2 yr. Old daughter of mine. Saturday just passed she decides to throw my phone in the water! Gotta love'em! Anyway a question I needed to ask was about the canabutter. I didn't dry my trim I just put it in ziplock bags and froze it. Can I still use it with good results?
