Recirculating vs Run-to-Waste Hydroponic Systems

What Is a Recirculating (Closed-Loop) Hydroponic System?

A recirculating system continuously reuses the nutrient solution. After feeding the plants, the water drains back to a reservoir, where it’s:

• Filtered
• Adjusted for pH and EC
• Optionally sterilized (UV, ozone, etc.)
• Pumped back to the plants

You’ll commonly see this setup in:

• NFT (Nutrient Film Technique)
• DWC (Deep Water Culture)
• Dutch Buckets with reservoirs
• Ebb & Flood (Flood and Drain)

Advantages of Recirculating Systems

• Up to 80–90% water savings compared to run-to-waste
• Lower long-term fertilizer costs since nutrients are reused
• Environmentally friendly — minimal discharge or pollution
• Precision control over feeding and nutrient balance

Disadvantages

• Higher disease risk — pathogens spread through shared solution
• More complex — requires filtration, pH/EC monitoring, and experience
• Nutrient imbalance over time as plants uptake minerals unevenly

Pro Tip: If you run a recirculating system, always invest in inline filtration and UV sterilization to protect against algae and Pythium.

What Is a Run-to-Waste (Open-Loop) Hydroponic System?

In run-to-waste systems, the nutrient solution is used once and then discarded or repurposed (e.g., for landscaping or non-edible crops). No reservoir, no recycling.

Advantages of Run-to-Waste Systems

• Very simple to operate — just mix nutrients and go
• Cleaner root zones — no salt buildups or stagnant water
• Better for organic hydroponics since thicker inputs can clog recirculating lines
• Can run totally off-grid with a fertigation injector (like Dosatron), a solar pump, and a one-part nutrient like Liquid Gold (Gold Leaf in USA)

Disadvantages

• Higher input costs — constant nutrient consumption
• Environmental impact if runoff isn’t managed properly
• Requires responsible disposal — never dump into drains or natural waterways!

Which System Should You Choose?

Final Thoughts

Both systems work brilliantly — the best choice depends on your scale, budget, environmental values, and technical confidence.

• Want maximum efficiency and control? Go recirculating (just manage your filtration and monitoring carefully).
• Want simplicity or off-grid capability? Go run-to-waste, but always dispose sustainably — your local farmer or garden will thank you.

If this helped you, share it with a fellow grower — and if they sent it to you, you owe them a beer.

And if you are looking for an excellent fertilizer to help out with growing in your new system check out Liquid Gold! An all-in-one solution that is taking the UK by storm.

Article by Dr Russell Sharp

If you would like to keep up to date with subjects just like this, you can listen to both our podcasts! Links can be found bellow:

Hydroponics Daily Podcast: https://podcasts.apple.com/us/podcast/hydroponics-daily/id1788172771

Cereal Killers Podcast: https://podcasts.apple.com/us/podcast/cereal-killers/id1695783663