My overall aim is to create a freshwater reef ecosystem based on similar principles used in marine reefs (but cheaper). Technically freshwater organisms should be easier to keep than marine due to the varying environmental conditions found in freshwater environments throughout the different seasons.
They can usually be found inhabiting canals, lakes, rivers and streams and require very clean water. Sponges are not normally found in small bodies of water e.g. small ponds. With a larger water volume the chemical pollutants entering the water are more diluted and cause the environment to be more stable. This is a very daunting task for the marine reef keeper because trying to replicate the stability of an entire ocean in a small volume of water is a very difficult task. This means using some of the ideas used in filtering marine tanks to create the correct conditions.
The sponges which I keep are native to the UK, but are also found in Europe and America.
I have identified one of the sponges as Spongilla lacustris. They were collected from a river and I keep them in a small tank with flowing water and low level lighting, Sponges in higher levels of lighting can use algae in symbiosis to provide nutrients and in return the algae living in the sponge receives a safe protected environment to live. Sponges can use toxic chemicals when competing for space to deter or eliminate other nearby sponges or organisms. This happened in my tank recently when I added a sessile bryozoan and it attached to one of my sponges after 4 days the sponge had killed it.
The tank has two filter compartments; one is filled with ceramic pieces over some perforated tubing with mesh covering the holes. This allows anaerobic bacteria to live in the lower O2 area of this filter which break down any build up of nitrates, based on the sand bed idea from marine systems and an idea from reef central advanced topics forums called CPW or continuous plenum wasting, this involves removing water from the anaerobic portion of the sand bed once a week. This removes any unwanted anaerobic by-products like hydrogen sulphide and built up levels of phosphate. In this filter compartment, instead of course aragonite sand I've used ceramic tubes to avoid increasing pH. The water is tested weekly for pH, Ammonia, Nitrite, Nitrate, phosphate and hardness.
The second compartment of the filter contains a powerhead with tubing fitted to the outlet to return water back into the main aquarium.
I feed the sponges on green water and aquarian goldfish flakes. The green water is cultured in a clear container on my window sill and is fed to the sponge using a 1mL plastic pipette. I take 2 aquarian flakes and add some aquarium water into a small container and suck up the flakes then squirt back into the container until it is completely pulverised and then squirt the pulverised flake into the return current of the powerhead.
I also have 4 jenkins’ spire snails, some isopods, brown and green hydra, daphnia (branchiopod), limpets, an orb cockle and a couple of caddisfly larvae which sponges tend to encrust to disperse themselves. There is also willow moss growing on the synthetic rock at the back of the aquarium. The aquarium is still developing and I am slowly adding more and more FW reef safe species.
Sponges can reproduce asexually by breaking off a piece of the colony and then can reforming into a new sponge colony, or they can reproduce sexually. In bad conditions they can produce a hardened seed called a gemmule which can lay dormant until favourable conditions return. This can be caused by pollution or by cold weather. This tends to happen to shallow water sponges. Sponges found in streams tend to have a short life span due to limited nutrients and sudden changes in environmental conditions such as flooding and draughts. They are also mainly found living under rocks to protect them from the streams fast flow.
