What do these terms mean?

I am wondering what do these terms refer to (in regard to hydroponics)

-Flushing
-Ec
-TDS

Pretend that you are explaining this to a 10 year old

 

i can only help with flushing. flushing is a period before the harvest where you stop feeding nutrients, so the plant uses them up from the soil/solution, and its body. this makes sure harvested bud will taste nice, not be harsh/slightly toxic to inhale, and become white ash when fully burned. without a flush, you get crappy weed that gets you high yes, but is a bitch to smoke.

the rest try to google.

 

^ had flushing pretty much right.

Flushing (growing medium) -> Basically watering to remove salts, excess nutes via runoff.

Flushing (Plants) -> the last 2-4 weeks of flowering using only water for watering allows the plants to use the remaining nutes in the growing medium and helps to clean the plant's cells.

EC - electrical conductivity. As the strength of the nutrients increases the EC increases as well. Water conducts electricity - water with a higher salt content conducts electricity better. EC is used in Europe while TDS is used in the States.

TDS - Total Disolved Solids measured in ppm (part per million) or mg/l. It is another method of measuring the nutrients in a solution.

Think of making hot chocolate - the more powder put in makes for a darker milk. The higher the TDS and EC values = higher levels of nutrients in the "feeding" solution.

EC & TDS represent the same thing 500 x EC = TDS. So if you were recommended to use a EC of 2.0 you could use your TDS meter and mix the solution to 1,000 ppm or mg/l.

 

Great info, thank you!

By the way an additional question I know have about flushing is:

should I simply replace the nutrient jug with water? Or should I water the plant from the top and let it clean out the roots?

 

You want to pH adjust plain water and fill the reservoir with it (total change not just topping off) For Soil you would just water from the top.

 

What are some good indicators that it is time to flush?

 

For Hydro you will routinely change the feed tank once per week. For flowering 2-3 weeks before harvest.

Forgot the main question For hydroponics because it is an exacting method by the time you will get an indicator (ie: overfertilization) the plant will most likely be dead. Mild overfert the burned tips will show. A pH and TDS meter are important. Ph test kits are cheap and TDS can be ballparked by following the directions on the bottle (just keep it ~ 800 ppm).

 

My take on your question gets a mildly different answer. When flushing, I prefer to water the medium with plain water. I'm in rockwool and figure that even though I've drained the reservoir there's still plenty of old stuff hanging around that never completely goes away. Flushing from the top down helps to get rid of some more of it. I've noticed that even after 2 or 3 flushes at once there's still traces of the old gunk around. I've never gone to an extreme llike adding food coloring to see how long it takes to 100% get rid of the old stuff (why), but the water remains a little discolored after 1 or 2 flushes. No big deal imho.