Cryptic Zones Can Be As Interesting As The Display Aquarium

Cryptic zones really interest me. Of course everything in relation to this wonderful hobby is of interest to me but there is something about life growing in complete darkness which I find exceptionally fascinating.

A cryptic zone is effectively a place in the aquarium or another aquarium connected to the aquarium system whereby the area is in complete darkness. This darkness allows for non light loving organisms to grow and fluorish.

In an aquarium with lighting above it this can be hard to achieve and lets face it to keep corals we need good lighting, however there are always places in the aquarium where cryptic zones are unintentionally created. These places can be areas in between rocks, under the rockwork etc. Not very exciting at this point I know, however over time various organisms start to grow.

There are other places as well in the aquarium which are also unintentionally created. These are what are called semi cryptic zones. These are very similar to cryptic zones with the exception that well it is not as dark – more like dusk than night time.

Other than the life which grows in these areas there is an added benefit. The organisms growing aid in the filtration of the aquarium and can remove excess nutrients etc from the water. The reason for this is that since they do not utilise light as an energy source. Instead they filter particulate matter from the aquarium as well as (dependant upon the organism) removing various nutrients.

In my opinion any thing extra which removes particulate matter and nutrients from the aquarium can only be of benefit. I am of the opinion that by increasing the variety of nutrient export within the aquarium can only be beneficial to the system. I like the [tag-tec]refugium[/tag-tec] as they are excellent at removing nutrients, I like the [tag-ice]deep sand bed[/tag-ice] for the same reason and as you have probably gathered I also like cryptic zones.

Having a mixture of nutrient export mechanisms will mean that effectively they will fight with each other and some areas will not receive as many nutrients as they would if other mechanisms were not present, however a natural balance will be created and the life within these various mechanisms will adapt to the ‘food’ available to them.

Here is the next benefit – if one of these mechanisms fails for whatever reason, in this example lets say that the algae bed in the refugium crashes then the other nutrient removal mechanisms (along with the protein skimmer) will assist in the sudden increase in nutrients which have been released into the water. If these other mechanisms were not present then you would have to rely very heavily upon the [tag-self]protein skimmer[/tag-self] and possible large water changes to bring the water quality back to acceptable parameters.

The biggest benefit for me though has to be the joy watching life slowly growing and forming within the cryptic zone. I have a simple small external aquarium attached to my system which is fed by the overflow from my main display aquarium. The cryptic zone is wrapped in back bags so that no light can enter into the aquarium. The water which enters the refugium is quite slow so that the particulate matter in the water can drop out of suspension down onto the waiting life forms below. I have some pieces of live rock in there as well as a very shallow sand bed. Over time various sponges have started to grow as well as many other life forms (some of which I am unable to identify). I aso decided to allow some of the aiptasia to grow just to see what happened and they have grown into quite attractive creatures. Some people might not agree with the aiptasia aspect but I just wanted to see what happened.

I like to look into the cryptic tank from time to time just to see what is happening and the landscape in there is quite spooky really. It looks like a picture from the moon or something – very barren yet covered in life.

One thing which I have noticed in the aquarium is that there is a very large population of ‘pods’. Much more than in the refugium. Why this is I dont know but there is definately more.

To be honest the cryptic zone is probably not something that the beginner to this hobby should realistically look at introducing straight away. Not due to skill level but due to the water in the aquarium system being too clean. There is simply not enough particulate matter in the system. This should not put you off however, you could still plan to have one in the future when your water is dirtier (if that is the right word) and you should probably understand what cryptic zones actually are.

I tried to take some pictures of my cryptic zone tank but with it being completely in darkness I could not get a decent picture – even with the flash on. I really need to learn how to take photographs. Sigh! one day.

  1. “I have a simple small external aquarium attached to my system which is fed by the overflow from my main display aquarium.” Pictures!

  2. Hi Jeffry,

    In my opinion that is a very good way to attach a cryptic zone to the aquarium. A cryptic zone requires food to function correctly, therefore it is best not to place it after the skimmer otherwise a lot of the food will be taken out. They need ‘dirty’ water. The good thing about having it fed from the overflow is that the water is rich in oxygen as well as being dirty.

    Yes I know I need to get some pictures done – I promise I will try and get some decent ones done!

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