I Can’t Afford Live Rock, Am I Being Cruel?

It’s exciting, setting up a new marine aquarium and at the same time it can be frustrating as there is a fair amount to sort out. Initially it can be confusing obtaining the information on this and that and what is actually needed followed by the actual size required. We get there in the end though and it’s certainly worth it.

One of the reasons why the aquarist is so careful when purchasing equipment is to make sure the eventual livestock will be adequately supported. It’s also to make sure the amount of money spent is necessary and not wasteful – nothing wrong there.

The aquarist eventually gets to that very essential support for the aquarium, the biological filtration. This is provided by bacteria and deals with the deadly ammonia and nitrite, also nitrate. These are generated within the aquarium by the livestock and the first two are killers. The only acceptable reading for these is zero. Nitrate is not deadly but can cause real problems if not controlled, such as excessive nuisance algae. The guideline maximum reading for nitrate for a reef tank is 10ppm (parts per million) and for a fish only 30ppm. Both should be as low as possible.

The aquarist’s discovery of the biological cycle (ammonia to nitrite to nitrate) and the recommended way of dealing with it gives rise to the ‘cruelty’ question. The modern recommendation is to use live rock. Why is it called ‘live’? The rock is loaded with the bacteria that deal with the above-mentioned ammonia, nitrite and nitrate. The aquarist knows that in the wild the fish live among rocks and this seems the best way of providing a top line environment. It is. Another advantage is that live rock can deal with, within reason, the full biological cycle (also known as the nitrogen cycle).

Live rock is expensive. Putting a couple of rocks in is not sufficient, there must be enough to support the livestock. Sufficient rock as quoted by the dealer could be just too much money. Should the aquarist give up and not proceed further because ‘the best’ will not be available? There’s a simple answer and it is ‘No’!

The requirement is to give the livestock a fully supportive environment. So there is a need for rocks so the fish etc can find security (and make the view for the aquarist more natural of course). They don’t need to be live. Wait though, don’t buy any rocks yet.

The biological cycle can be achieved by using a powered cylinder filter. This is a unit that has an integral pump sitting on or in a cylinder that is filled with biological filtration material. Well, that’s not completely correct, there is filtration material to remove debris first to protect the biological material. It is necessary and really important to make sure that the lift rate of the power filter is sufficient to take the seawater to the highest point required, often the top rim of the aquarium. This distance can be quite large as most power filters sit below the aquarium in a cupboard. Manufacturers often give this information.

The power filter price is acceptable so all is sorted then. Yes it is but there has to be a downside of course. Live rock will deal with the complete biological cycle. The power filter will not, nitrate will be produced in the aquarium but not removed by the filter. Why? The bacteria that deal with nitrate require an oxygen poor environment, this is achieved deep in the live rock but the seawater flow through the power filter is oxygen laden. The nitrate has to be controlled by not overstocking, not overfeeding and completing regular partial seawater changes. These are required anyway so it isn’t a big deal, though the partial seawater changes could need to be a little larger. The guideline for these is 10% weekly of the total aquarium gallonage including a sump if present. The amount can be adjusted as the aquarist’s experience grows.

Ok, the power filter it is then. What of the rocks? Natural cycles occur within the aquarium and bacteria that are required for the biological cycle are present within the aquarium up to a point not just in the power filter. So when the rocks are bought don’t buy solid dense lumps, get craggy porous ones of various shapes ensuring they are marine aquarium suitable. They shouldn’t be powdery or flaky. Once the reef is made, leave them alone apart from any initial necessary adjustments. These rocks will become home to bacteria and will also be able to house those that deal with nitrate as they are deeply porous. This takes time and requires patience, it will not happen overnight or over a few weeks. I did this and it took 10 months before I could safely turn off the power filter (well, remove the biological material anyway, the power filter is still in use).

To check for rock becoming live is easy but great care is required. Once the rocks are aged for many months or even up to a year the power filter can be turned off and a very regular check for ammonia, nitrite and nitrate done. Any sign of the former two and the power filter is back on. WARNING – There is a danger and it is real and needs attention. If the power filter is turned off and the rocks are not sufficiently ‘live’, the power filter needs to be turned on again. If the power filter has been turned off for a good while the biological capabilities of the filter could be seriously damaged and the livestock could be in danger.

To mainly avoid the above described danger the aquarist could have initially obtained two smaller power filters (remembering to check for the lift capability). They are both loaded with biological filtration material. When the time comes to try turning them off turn one off. Leave the other running for a month or more. Test for ammonia and nitrite. When all is found clear for a month or more turn the other off. Continue testing. The bacteria on and within the rock should increase as the impact of the power filters is removed. Don’t take chances, patient testing and time is required.

The aquarist could be quite happy to leave the power filter running, nothing wrong with that. The livestock will be quite happy and healthy, fish and/or corals. It just means a little more maintenance, including cleaning the filtration material in the power filter on a regular basis (only the initial filter material to remove debris, not the biological material! The debris material can be cleaned under a tap. If absolutely necessary, the biological material can be very gently washed in aquarium seawater). Also perhaps there could be a need for larger partial seawater changes to reduce nitrate.

Some requirements for the marine aquarium are essential, such as heater(s), circulation pumps, protein skimmer etc. Rocks make the scene look natural and also provide hiding places for the livestock which reduces stress. If ‘live’ rock can be used, great. If not then ‘dead’ porous rocks could be obtained and when they have coloured up they’ll look lovely. If power filters are in use for biological filtration and the aquarist has doubts or worries about turning them off, don’t.

(Photo: aquariumillusions.com)

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