Improve Your Operations with Growstones

Aquaculture is the farming of fresh water fish under controlled conditions. For fish to remain healthy and grow at a favorable rate, they must be provided a suitable environment. In aquaculture, this means the quality of the water needs to be kept. When growing fish, in closed systems, the water quickly becomes nutrient rich due to the fish digesting their food and excreting waste. Biofilters are used to help maintain water quality. Biofilters help remove dissolved and suspended waste products and facilitate the attachment and growth of nitrification bacteria.

There are multiple types of Biofilters used for aquaculture applications. Most are made from polyethylene and are expensive. Looking at more sustainable and less expensive but suitable alternatives is important.

This clip shows tilapia grown in a closed recirculating aquaculture system using an alternative Biofilter made from recycled foam glass characterized by a very large specific surface area “packing density”. In this eight week-long trial, the efficiency of two Biofilter materials was compared – a recycled foam glass (Growstones) and plastic bioballs.


Water quality parameters of all fish tanks was monitored weekly for water temperature, dissolved oxygen, ammonia, nitrate, total soluble solutes, and pH.

During the entire experiment, water quality was very high and no differences in water quality were observed between the two Biofilter. Given the high surface area characteristic of Growstones, it is likely that only a small proportion of Growstones per volume of Biofilter is needed to accomplish the same results. This would also help increasing the void fraction allowing for free and unrestricted flow of water and air through the Biofilter.

These results are encouraging and suggest that a recycled material may replace plastic bioballs for Biofiltration with no negative affects and at lower cost.

For additional information on using Growstone in an Aquaculture system, please read the following report from the University of Arizona:

Efficacy of Growstone as a Filter Medium in Aquaculture Applications
Summary: As a recycled glass and having a large surface area to volume ratio, Growstone is a relatively better and more cost effective option compared to other bio-filers used in Aquaculture systems. The University of Arizona, Environmental Research Laboratory, Tucson AZ, 2009