Categories: Filters, Shellfish Tanks634 words2.4 min read

Maturing your Lobster Tank Filter


Errin Todd


February 22, 2017


A filter is essential on your lobster tank.  It keeps the water clean and clear and removes waste, bacteria and toxic ammonia.

We are aware of many fishermen (and a few merchants) who try to keep lobster in aerated tanks and keep changing the water rather than put a filter on their tank.  Unless you have a fixed pipeline to the sea which always has clean water free from pollution this is risky.  The cost of the vehicle, bowser, generator, pump, hose etc not to mention the man-hours to do this does not make economic sense.  Investing in a filter will be the best move you can make.  Whilst all of our systems come with our unique six-stage filtration we can also supply filters to customers who already have tanks.

Today I want to explain more about filter maturation.

The biological filter takes time for the good bacteria to grow and multiply.  The biological filter turns toxic ammonia into nitrite then less toxic nitrate.  The bacteria which do this essential job can take weeks to reach the numbers required.  The bacteria like warmer temperatures than lobsters and will multiply best at 20 degrees centigrade.  However they also need some ammonia from the lobsters wee to feed on but this temperature is too warm for lobsters to thrive.  Keeping your system at between 10 and 12 degrees centigrade for this maturation period is the best compromise to get good bacteria growth and also be within acceptable temperature range for holding lobsters.

We use RK Media in our biological filter.  This is a small, black, plastic circle with lots of surface area for the bacteria to grow.  The media is put within our filter tank which has a rounded bottom and aerated from below to move the media around.  This motion brushes off old bacteria which is less effective.  This makes the filter self-cleaning and very efficient.  When we supply our filters we aim to ‘seed’ the biological filter with some mature media from our systems.  This helps to kick start the process.

When you get you new system we recommend putting up to 1/4 of the full capacity of crustacea into the tank.  Ideally lobsters first as crab can be very mucky and a mature filter is best to deal with them.  The shellfish holding tanks will maintain the quality of your shellfish but they are not life support machines and may not revive a lame, weak or recently cast lobster.  The better the stock quality you put in the better.  The old IT saying, “garbage in, garbage out,” is true here.

Check the stock every day and test the water daily for the first week or within 24 hours of putting new stock in.  Initially you will see higher (although not unsafe levels) of ammonia in the water test readings.  Only when this is 0 should you add any more stock.  Eventually after a few weeks your filter will be full of good bacteria which can deal with the toxic ammonia and you can operate the system to full capacity.

We often get asked how long this process takes and it is hard to guesstimate as the process is dependent on stock levels, species and quality as well as temperature and seawater quality.

On average our customers take six weeks to get a system fully mature although one repeat customer followed our advice and used our water testing service twice weekly and achieved full maturation within three weeks. Well done to high achiever Nick!

We know that some of the science can be daunting if you are new to holding live shellfish but we are here to support you and give you the benefit of our experience.  Please call us if you have any questions and ask for Keith or Laura Tel 01383 820685.

Best Fishes,


Todd Fish Tech Ltd