So, one more month has seemingly flown by as the UK increasingly continues to return to some form of ‘normality’ post-lockdown. Amongst many other things, we are now able to get a hair cut, go to a restaurant and sip that first draft pint for almost 3 months. For many, this feels far too rushed, whereas others cannot wait to get back to the life we used to have pre-COVID. I guess there is no right answer to this, but one thing is for sure, we all need to remember to be responsible for our behaviour and respect others at all times.

COVID Store poster

Since we have fully reopened, we have been delighted to welcome back such vast numbers of customers into our stores. Obviously, we are doing our very best to enforce all the necessary government guidelines and would kindly like to remind everyone to please observe these when in our stores. We very much appreciate that having to queue to enter many of our establishments is by no means ideal and can be very frustrating. But please try to remember that our staff are doing their very best to ensure the welfare of you, themselves and their colleagues whilst maintaining our highest standards of customer service that you have no doubt become accustomed to when in-store. The general feeling is, we are by no means at the end of this so the responsibly does fall directly onto each and every one of us. A sobering reminder happened earlier last week in Leicester, where we have a store. Even though this store is within the localised lockdown catchment area, we, fortunately, can remain open since we are classed as an essential retailer. That said, we continue to ask our Leicester customers to please only visit this store if absolutely essential. That way, it will enable us to remain open and allow local fishkeepers to service and maintain their ponds and aquariums throughout this period.

This month I wanted to focus specifically on one new product that we have acquired exclusively to Maidenhead Aquatics: the Ocean Free ‘Activa’ block - a super-charged activated carbon block ( Carbon has been used one way or another in all types of aquariums for many decades, and most of us will know it as the black granular media used in the multitude of aquarium filters. But I’m sure many fishkeepers actually don’t know why it’s there and what it actually does?

Activa Carbon BlockCarbon, or more specifically, activated carbon works in the aquarium by the adsorption (the process by which a solid holds molecules of a gas or liquid or solute as a thin film) of certain chemicals that come in to contact with its surface, and the reason why the amount of available surface area of carbon is so important. Therefore, the more it has, the more it can remove from the water. Due to these adsorptive properties, activated carbon will inevitably become exhausted as the surface is coated in waste. Dependent on the levels of substances within an aquarium, the carbon might be exhausted within 3-4 weeks. In this case, we would recommend replacing normal activated carbon regularly to prevent the possibility of some of what has been removed from leeching back into the aquarium again.

Activated carbon is specifically good at the adsorption of ORGANIC chemicals (generally any chemical compounds that contain carbon-hydrogen bonds with or without oxygen, nitrogen, sulphur, phosphorus, and other elements) from the water, and a couple that it is particularly excellent at removing are phenols and tannins. These arise from a number of sources within an aquarium, including the metabolic waste of fish, uneaten food, decaying plant and leaves, and can leach out from decorative wood. These organic compounds tend to discolour the water, giving a yellowy-brown tint, and in the case of phenols, emitting a 'musty' smell to your aquarium. Therefore, activated carbon is the perfect addition to any aquarium for 'polishing' water to achieve crystal-clear clarity and remove any odours. In freshwater aquariums, excessive organic compounds will cause fish to become weak and more susceptible to illness. This tends to happen gradually over time, where fish are exposed to levels over a long period. In marine aquariums, it has been proven that such organic compounds will affect invertebrate growth and the general wellbeing for all inhabitants. One other underestimated benefit of activated carbon is the removal of chlorine, chloramine and some heavy metals from water, which is essential to achieve a healthy bacterially-laden filter and therefore a thriving aquarium.

And unlike some other companies that are advertising these as the ‘magic bullet’ for any aquarium (where you amazingly no longer need to change the water, don’t require a filter, or you can even recharge the block but “simply washing them in soapy water”!),  let’s make it clear, it will not remove ammonia, it will not adsorb nitrite, and it will not touch nitrate. It does not allow you to skip any of the fundamental principles and processes behind keeping and maintaining a healthy aquarium. Instead, what we are claiming is that this is an amazing aquarium carbon, in fact probably the BEST aquarium carbon money can buy!

After trialling this in my reef aquarium for a number of months, I firmly believe that the Ocean Free ACTIVA BLOCK has to be one of the best carbon medias available on the aquatic market today. And believe me, I have tested the majority! This super-charged activated carbon block is designed to maximise the absorption of aquarium water discolouration, odours, toxic pollutants (e.g. chemicals) and medication, and is ideal for ALL types of aquaria.

Highly porous natural bamboo activated carbon and sepiolite clay minerals (a naturally occurring clay mineral of sedimentary origin. It is a non-swelling, lightweight, porous clay with a large specific surface area) are precision cut into a cuboidal matrix design, featuring 1400 micro-tunnels. This greatly increases its surface area and boosts its ability to draw out toxic pollutants from your aquarium water quickly and efficiently. As a result, one cube has the equivalent absorptive capacity as 40 times its weight of regular activated charcoal powder. Therefore, the 250g cube absorbs to the same capacity as 10kg of regular activated charcoal powder and the 500g cube to 20kg. Absorption test results carried out by the US EPA Methylene Blue Method shows the 250g block can absorb 1mg of Methylene Blue within 3 hours. Now that’s an impressive set of statistics! (

Other advantages are that the Ocean Free ACTIVA BLOCK requires no pre-rinsing or usual filter media bags for it to be housed within- simply place the block into your aquarium or sump and you’re done! The smaller 250g block is recommended for aquariums up to 150 litres, with the 500g block up to 300 litres respectively, and if you require more, simply lock blocks together to achieve the right amount. So easy. And due to the huge adsorption volumes of the blocks, we would recommend replacing an OF® ACTIVA BLOCK every 2-3 months, which is longer than the traditional aquarium activated carbon. [N.B. due to OF® ACTIVA BLOCK's amazing adsorption properties, it will absorb many different aquarium medications, preventing these from treating your fish. Therefore, if you plan to medicate your aquarium, you must remove all forms of activated carbon. Once the course of medication is complete, return the OF® ACTIVA BLOCK to remove any leftover treatment from the water. This is also one very good reason to have an OF® ACTIVA BLOCK at your disposal, in case you ever need to remove any accidental medication overdoses].

Activa Stacking Carbon Blocks

Anyway, I sincerely hope you have found this of interest and want to try one in your aquarium soon. Being available to purchase both in-store as well as online, we’re certain your fish will thank you for it!

Until next time, please stay safe and well, and keep enjoying this amazing hobby!