I am not too happy with my sump, but since Barries asked me to show it, here it is. I will first explain the principles and how I build it, and below what is bothering me about it, ie mistakes I made.
First picture shows the sump in full length. The principle was to not have a up/down water flow, but a wide birth like a river, with water running straight through from one side to the other. The up/down type speeds up the velocity of the water flow, like rapids in a river, which I do not want, as I want the water to be exposed to the bio media for as long as possible, to give the bacteria time to do its work.
[You must be registered and logged in to see this image.]The next picture shows the compartments a little better. The first stage is where the overflow from the tank comes in and the water get aerated. I feel it is important to aerate here as much as you can, as the oxygen is needed for the nitrification process in the bio media. The bacteria need the oxygen to turn ammonia into nitrite. (NO2)
The next compartment is the mechanical filtration and consist of filter wool and mat. All the 'big' waste is filtered and captured here. It looks small, but the with gives you considerable volume and once again, because the velocity of the water is slow, so much more dirt is captured.
Then I have a compartment for whatever my need is at the time. Here I am using Zeolite to try and compensate for the heavy overload of fish (Angel Fry) I had. They were producing a lot of ammonia, but my sump handled it eloquently, with the result that I had a build-up of the final element, nitrate. (NO3). I heard that Zeolite help to absorb it, but I found that it does not make a noticeable difference. The only way to effectively get rid of nitrate is to do water changes. At this stage I had to do 50% water change every second day. Any case, this compartment can be used for whatever your need is, like activated charcoal for instance.
Next chamber is just visible as its front part and you can see how big it really is in the first pic. Here I use Seachem Matrix as my bio media. Matrix is very porous and gives the most space for bacteria to live on. You need oxygen rich water flowing slowly through it to perform at its maximum. Colder water can contain more oxygen than warmer water, that is why the heaters is in the last compartment, just before it is pumped back to the tank.
The pump itself must be adjustable and strong enough to keep up with your overflow and keep the water level in your tank where you want it. I think it is virtually impossible to get this right if your pump is not adjustable.
[You must be registered and logged in to see this image.]Another thing to keep in mind when you design your sump is that it must be big enough to handle all the water that will overflow to it when there is a power failure. In case of a power failure, your pump stops working and no water is returned to your tank, yet the overflow keep on flowing till it stops at the lowest level of your design of the overflow. The overflow deserve its own thread and I will start one with mine. Bossie told me of a nifty way how to manipulate it, but we can discuss it there.
What I do not like about my sump:First of all, it is not deep enough. I find it difficult, but not impossible, to keep the level where there is still enough room to take the volume of water in case of a power failure. We had quite a few power failures up to now and I had not one overflow. Yet, if the sump was higher, it could be easier.
Then, there is not enough space between the sump and the tank. It makes it difficult to work in the sump and to add water, as you must do top-ups. My pump keep the water level in the tank at the full level and thus, I must replace evaporated water on the sump side. The only way I can get water in there, is to pump it in from my container. If there was more height, I could have poured it in with a bucket. Sadly I had no choice in this aspect, as that is the space my stand allowed me.
The size of the bio material compartment is way to big. I have about 8 liters of Matrix in here, which is way overkill for my 4 foot tank. I should rather have made this compartment smaller and added another compartment for same other function as and when needed.
Minimum size of a compartment must allow your fist to have room in it, otherwise it is difficult to work in it and clean it.
Lastly, I would love to have a system that automatically add water as it evaporates. The problem is that evaporation cause the level in the sump to drop, which cause your top layer of bio material to run dry and bacteria dies off in the media that runs dry. So you never have maximum bio material populated with bacteria. If you add water automatically, the level will always be the same. The reverse is also true. If the level in the tank is higher than your media, the water just runs over the media and not through it.
Well, all that said, the sump is still pretty effective and does a good job.
Building the sump.[You must be registered and logged in to see this image.]Divider.[You must be registered and logged in to see this image.][b]