In earlier posts I may have mentioned gravel washing. Let me elaborate on this.
First you might ask Why? Why would one wish to wash the gavel before putting it into an Aquaponics System?
First, because we want to keep our grow beds fairly free flowing and having sand and clay filter down to block up the bottom of the grow bed will keep air from being able to get down there and water doesn’t flow though sand and clay nearly as well as it will through gravel. We wash the media to get rid of the “fines” that would otherwise clog the bottom of the bed or even get into the plumbing to clog plumbing and even wear out pumps.
Second, if you don’t know what effect the sand/dust/clay will have on your Aquaponics system, you don’t want to put too much in. For instance, if the dust mixed into your media has a large amount of lime in it, that will affect pH in the system for a long time to come. Gravel in a big pile at some supply place might be sitting next to a large pile of crushed limestone/concrete and be near the crusher even. Now perhaps you got a sample of the stone and rinsed it then tested it to make sure the media wouldn’t affect your pH but if you don’t rinse the gravel going into your grow beds, you might be dumping excess dust in that will affect the pH for quite a time to come.
Finally, even systems filled with clay balls usually have the media rinsed once and that water let run to waste before hooking up to the system because if you don’t do this, the water will stay cloudy far longer than most people like. Even with washed media, the water still clouds for a time after filling.
So, now that we have gotten past the WHY, Here are some options of HOW.
For river rocks that has mostly just a mix of sand in it, swishing a basket full of pebbles in a couple bins of water before putting into the grow beds works very well. A few tips, set up the bins of water at a comfortable working height so you are not bending while working and don’t over fill the baskets.
For other media like cinders or expanded shale, dry sifting might be more effective since light small particles like clay stick to things when wet but will drift away when dry.
Now my favorite way to wash gravel!!
Throw a party, workshop or event. This is what I did this past weekend. I offered a “Free Workshop” where people could come and I would show them something about laying out and plumbing together part of an aquaponics system and in turn they got to have lunch and become initiated into Aquaponics via gravel washing.
I thank everyone who attended my 300 gallon Aquaponics System Expansion Workshop.