About The Bathtub Method

This method is much easier than the shower method but you may not have a shower. The shower method can also be done outside.

Why Use Hydroton

I use hydroton as the medium for my system, instead of soil. This supports the Rockwool cubes and the plant’s roots when they eventually grow out of the cubes. It also slows down the water draining from the plants in my ebb & flow system which pulls fresh oxygen through and into the roots during every watering. Advantages:

  • Retains water/stays moist – because it is porous
  • Promotes oxygen circulation/great aeration
  • Slows drainage
  • Inert/PH neutral (odorless too)
  • Preventative – for rotting, excess acidity, and pests since it does not hold onto these things
  • Reusable
  • Affordable – $50 for a 50L bag

For this grow I am still going to use trays one last time before switching to a bucket system. This requires a lot of Hydroton and it should be cleaned before you use it.

Why You Should Clean Your Hydroton

When you pour Hydroton out of the bag you may notice that it is covered in red dust and other ‘crud’. This crud will clog up your system and eventually cause problems. This is why you should clean it first.

I also think it is a good idea to disinfect the pellets since you never know how long the bag was kept on the shelf and under what conditions. It is just an extra precaution and I have heard a lot of people skip it completely. I don’t just to be safe, plus it doesn’t take too much extra effort.

What You Will Need

  • A bathtub
  • Sink drain/hair catcher and regular stopper
  • 1.42 gallon container of bleach
  • Grow room measuring cups
  • Stick or dowel a foot or two long
  • 3-5 gallon bucket with holes drilled in it (see Step 1 from shower method)
  • Hydroton storage unit or grow tray
  • Rubber gloves if you want


The Process

Step 1 – Rinse the Hydroton

Place the sink drain/hair catcher into the bathtub drain then pour up to 50 L of Hydroton into the tub (I have to wash two bags so I do this whole process twice).

Hair Catcher Hydroton

Turn on the water and fill the tub with water (it will still fill up since the Hydroton slows the drainage, just make sure to cover the drain up with the pellets first).

It will take about 2 minutes for the tub to fill up then start stirring the pellets while leaving the water on. This will clean all of the dust and crud off of the pellets and put it down the drain or the bottom of the tub.

Bathtub Method

Do this for about 5 minutes then turn off the water and let it drain. Drainage takes about 5 minutes.

Step 2 – Sterilize the Hydroton

After the water has drained out switch the hair catcher out for the regular stopper by pushing the pellets back.

Fill up the bathtub with water, adding 3 cups of bleach. Soak the Hydroton for about 30-60 minutes. Drain completely.

Some people soak them overnight but I do not think this is necessary for first time use.

Step 3 – Rinse the Hydroton Again

Again, switch the regular stopper for the sink drain/hair catcher and turn on the water filling the tub with fresh water to rinse the bleach from the pellets.

Keep stirring while the water runs to get a good rinse. Do this for about 5 minutes then turn off the water and let it drain. Repeat 2 more times, but stirring for only 1-3 minutes and then letting the bathtub drain completely between cycles.

Step 4 – Transfer the Pellets

Use your filter bucket to pull out bucket fulls of pellets at a time. This will also effectively separate the rest of the crud out, which you will eventually see at the bottom of the tub.

If you want you can run the pellets under the shower one more time to ensure a good rinse before transferring the Hydroton to your storage bin or grow tray. Do this until your tub is empty and your Hydroton is ready to use!

You may want to leave the pellets out in the air for 24-72 hours to let any left over bleach dissipate before using it to be extra safe, but I have never done this purposefully.

Now clean your tub, it is filthy!

Notes and Tips

  • Make sure everything you use is cleaned and sterilized first, including the tub
  • Make sure your hair catcher and regular stopper fit your bathtubs drain, this makes it much easier because then it will not slip out of place on you!
  • If your tub doesn’t drain like it should you may have a bunch of smaller pellets caught in the hair drainer, just use your hand and pull them out and it should start draining again
  • I usually end up using my glove covered hand to stir instead of the stick because it seems more vigorous
  • Use plain bleach, not any kind with scents or any other additives
  • I decided on this percentage bleach to water after reading a lot of different forums, spending way too much time. There were too many conflicting opinions so I went between “sanitizing” and “disinfecting” strength listed on the bottle! Seemed safe and was middle of the ground on most people’s opinions
  • Have a measuring cup just for the grow room so you dont have to contaminate your kitchen ones with chemicals. I use one of the 2 cup glass ones so it can be easily sterilized


  • Benefits of Hydroton by Michael Straumietis