Run to Waste (RTW) vs Recirculating Hydroponic Systems
Hydroponic growing is rewarding, especially when plants are fed with a reliable system that supports healthy growth.
Many new and experienced indoor growers ask the same question: which hydroponic feeding method is the most reliable and rewarding?
Two of the most common indoor hydroponic feeding methods are:
- Run to Waste (RTW) hydroponic systems
- Recirculating hydroponic systems
What Is Run to Waste (RTW)?
Run to Waste, or RTW, is a hydroponic feeding method where a brain tank or main reservoir is mixed to the correct grow week at maximum dose.
In an RTW hydroponic system, the pH and EC target values generally do not change. This means every feed delivered from the reservoir is at the intended strength.
For smaller hydroponic setups, nutrients are usually added to fresh water daily at the maximum strength recommended for that grow week, then fed directly to the plants.
The “waste” part of Run to Waste means plants are fed until run-off is produced. This is usually around 10–20% of the pot’s holding capacity. The run-off solution is then disposed of and is not re-fed to the plants.
This helps remove built-up nutrient elements that were not used during the previous feed.
What Is a Recirculating Hydroponic System?
A recirculating hydroponic system reuses the nutrient solution, making it an efficient way to feed plants while reducing water and nutrient use.
This can make recirculating hydroponics a more cost-effective indoor growing method. However, it does have some challenges.
For a recirculating hydroponic system to perform well, the target EC and pH values should remain stable as the reservoir volume reduces. This can be difficult to manage without experience.
Once a recirculating system is running, the main concern is usually rising pH combined with falling EC.
If the pH and EC change, nutrient uptake can also change. When pH rises, some nutrient elements may not be absorbed properly. Growers who top up EC with nutrients during a live recirculating system can run into problems, including minor deficiencies that may progress due to nutrient antagonism.
Some recirculating hydroponic systems are designed to operate with a lower EC. For growers considering this setup, it is worth speaking with a local hydroponic shop about suitable branded recirculating systems.
Which Hydroponic System Is Best?
The best hydroponic system comes down to grower preference.
For indoor growers focused on results, consistency and fewer problems, Run to Waste is often the preferred hydroponic feeding method. RTW gives the grower full control over what is fed to the plant at each feed.
Recirculating hydroponic systems are more efficient in terms of water and nutrient consumption. However, issues can occur when the same nutrient solution is re-fed to the plants.
Both RTW and recirculating systems have advantages and disadvantages. Many hydroponic growers will find a use for both methods, depending on the crop and indoor growing setup.
Much love, and keep growing!
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