Exclusive Behind-the-Scenes Tour!

I had thought about doing a post on the “back of the house” of the fish tank so to speak, and tonight I got in the mood for whatever reason. If you ever wondered exactly how everything works, how the water stays warm, how the plants grow, etc., here’s the inside scoop.


The lights seem like a good place to start! I run two Ecoxotic LED lights over the tank. They originally cost about $300 a piece, but I got lucky and bought them on clearance for about $65 for the two together. I believe I bought the mounting hardware separate. I’ve had enough tanks where the light just sits on top of the glass cover that I didn’t want to do that anymore; it makes maintenance such a pain. So both lights are suspended from the ceiling, meaning I can get my hands in the tank without disturbing the lights.

The lights are both operated by remote control. If I feel like doing gymnastics, I can usually get one remote to control both at the same time. Pictured below are the two receivers for the lights. The receivers are honestly pretty useless past showing the time (and even then, one runs faster than the other). I have to use the remote to change any settings on the lights. Since they are LEDs, the color possibilities are nearly endless! I have also set sunrise/sunset times so that I don’t have to manually turn the lights on and off every day – also, this provides a reliable and appropriate photoperiod for the plants.

You can see the little wire shelf stand-thingies at the ends of the light here, to be used if you wanted to set the lights on top of a tank rather than hang them. Supposedly those come off, but I’ve not managed to make that happen yet.




For plants to grow well, you have to find the balance of three separate elements: lights, carbon dioxide, and nutrients. I have not found that balance yet (and I suck at remembering to dose fertilizers), so you’ll find some Black Beard Algae in my tank, as well as the occasional slightly yellowed leaf.

I do try to fertilize on the reg, but I suck at remembering to do so. I use dry potassium nitrate and monopotassium phosphate, as well as liquid iron and a pre-made liquid mixture of micronutrients. I also dose some with API CO2 Booster or Flourish Excel, whichever I have on hand, to help decrease algae growth and boost the carbon dioxide a little – particularly on the end of the tank opposite my carbon dioxide diffuser.

I put together a relatively simple carbon dioxide diffusion system. Here you can see the CO2 tank with the solenoid regulator on top (it’s the one on the far right – the black cylinder in the middle is a filter, which we’ll get to later):



The regulator allows me to alter the pressure of the CO2 coming out of the tank aside from just manually turning the knob. Since it is electric, it also allows me to attach the CO2 diffusion system to a light timer on the wall (pictured at the outlet there), similar to what you might use for your Christmas lights, to only diffuse CO2 when the lights are on. Plants cannot use CO2 when they don’t have any light, and if the plants aren’t using it, then it just stays in the water. Believe it or not, fish can and will suffocate. As such, my timer switch there turns the CO2 on and off at times that coincide with the lights’ sunrise and sunset. Since the pressure is set on the solenoid, this system is effectively hands-off once you find the sweet spot on the regulator for the amount of CO2 you want to diffuse.

You may be wondering how exactly you set how much CO2 to use – well this delightful little glass contraption below does just that!



This is both my diffuser and my bubble counter. It’s attached to the inside of the tank with a suction cup. The tube coming from it goes out of the tank and down to the regulator, which you can see above. The tubing I have running to the diffuser is presently clear, but you may notice that the tubing from the regulator is blue. That’s really just coincidence; there is a check valve installed, which involves connecting two separate lengths of tube to either side of the check valve. This just prevents water from backing up to the CO2 tank when it’s off.

So on top of the bubble counter/diffuser sits a little porous piece of ceramic that works to break up the CO2 into tiny bubbles (which you can sort of see pictured) so that it’s better absorbed in the water – that’s the diffuser part. The glass cup beneath the diffuser is the bubble counter. When CO2 gets to the cup, it comes out of the tube in the form of bubbles (the cup is filled with water so that you can see the bubbles) Based on how many plants you have and what kind, how big your tank is, how religious you are about dosing fertilizers, how much light you use, and other factors, you figure out how many bubbles you want per minute (or per second), count them as they come through the glass cup, and adjust your regulator accordingly until you get the desired amount of bubbles. Mine diffuses about 3-4 bubbles per second.

Since CO2 can be dangerous to fish if left to build up, I take extra precautions by also having two airlines run to the tank from a bubbler. Here’s my Azoo bubbler (the little greyish box to the left; the big grey box on the right is another filter, which I’ll get to shortly):


It has Hi and Lo settings and also has two compartments for batteries. That way, if the power goes out, I still have air and water movement to help keep my fish and beneficial bacteria healthy. You can certainly buy smaller, simpler bubblers that just plug in the wall and go.

Here’s one of the two air stones the bubbler connects to (essentially another diffuser):


Any air lines run into a fish tank should always have check valves on them to protect electrical equipment on the other end and also to prevent fires. All of my air lines have a check valve installed; they usually only cost $1-$3 depending on where you get them and what brand. It is worth it to check on them occasionally and make sure there is no water between the check valve and the electrical equipment; I have had one fail before.

On to filtration!

So, in the above pictures, you saw my two canister filters. I run two Eheim brand canister filters, though they are different models.

Before I jump into my setup, let me break filtration down: in a nutshell, you need something attached to your fish tank that the water will be pulled into and then run through filtration media (i.e., filter floss, sponges, little balls designed to have lots of surface area for good bacteria to grow, water-polishing agents such as Purigen, etc.) before being returned to the tank. There are such things called sponge filters that don’t pull water through them so much as just provide water movement and surface area-heavy sponges for bacteria to grow on, but I digress. Here, we are talking about canister filters.

Filters are so important because this is where most of your good bacteria lives – the stuff that chomps on the ammonia generated from fish waste and ultimately turns it into nitrate, which is much safer for fish. A good, established filtration system will always keep your ammonia at 0 ppm by hosting lots of good bacteria on media that is specifically designed to house said bacteria. In addition to changing ammonia to nitrate, called “biological filtration,” filters also provide mechanical filtration – i.e., it removes solid waste and debris from the water and catches it in sponges or floss. You can also add chemical filtration to a filter which can directly remove/neutralize ammonia, or, like carbon, remove or neutralize medications and other chemicals in the water. I personally only use biological and mechanical filtration.

So, if you were to look inside my filters, you would find various media stacked in layers in the canister, each with its own purpose. I also use Purigen, a water-polishing agent, and I keep crushed up shells in the filters to buffer the water’s pH. The filter basically holds anything you want the water to be run through.

Here you see a filter intake (the vertical green pipe) that sucks water in and through tubing down to the canister filter on the floor, and the filter output, in this case a spray bar (the horizontal green pipe) that returns the water to the tank once it has run through the media inside the filter:

These are closer together than I might have liked, but my thick fake-rock background makes it difficult to place equipment along the back wall.

Here is the other filter intake (the grey thing behind the wood):


And its output, another sprayer bar:



The sprayer bars just ensure that you don’t have basically a hose blowing water into the tank and creating violent currents.

Now, as far as heating goes, I have a more elaborate system than most. In the interest of heating more evenly and also in reducing the equipment clutter in the tank, I utilize “in-line” heaters. More typically, you’ll see submersible heaters, which are literally long, thin, cylindrical elements that directly emit heat that you just put down in the water. This can lead to hot spots and cold spots if you don’t have good water circulation – also, they can be a pain to hide if you’re going for a natural look.

I use two heaters, each attached to a canister filter’s tubing. This is what they look like:


So I basically cut the tubing running from my canister filter in half and put the inline heater between the two halves. Now all water that goes through the canister filter also runs through this heater. It is recommended to install these heaters on the output tubing (i.e., the tube that runs from the filter with clean water back to the tank) to reduce the amount of debris that comes in contact with the heating element. Due to problems with different tubing sizes, I have one inline heater installed on the output tube of one filter, and the other one installed on the input tube of the other filter (the output tube of that filter did not match up with the inline heater). So far I’ve had no issues.

These heaters are both electrical, and as such need to be plugged in. Now, for a couple reasons, I have again done this in a more complicated way. For one, I wanted even heating. I wanted the whole tank to be the same temperature – meaning I wanted both of these to be set to the exact same temperature and to turn on and off together at all times. For two, these heaters have a reputation for failing, which involves cooking all the fishies.

So, rather than just plug each into the wall separately and letting it do its thing, they are both plugged in to an Azoo temperature controller. (Sidenote: I really love the Azoo brand. The instructions are usually in the worst Engrish you’ve ever seen and barely legible, but the equipment works great!)

Here is the Azoo temperature controller:

Sorry the lighting from the LEDs caused some exposure problems there. So basically, I set the desired temperature for the tank on the temperature controller – so I want my tank to be kept at 26* Celsius. The Azoo temperature controller has three cords coming off it. One runs to a thermometer that is placed in the tank here next to this attractive dead leaf:



The thermometer actually has a suction cup on it, but again, it’s hard for me to place equipment sometimes due to the fake rock wall, so it just sits down on the substrate instead.

One other cord from the temperature controller basically runs to a miniature power strip – so I can plug three different heaters into it.

The third cord runs to an actual plug that goes into the wall.

Rather than the heaters detecting the temperature of the water moving through them and turning on and off accordingly, which is how they’re supposed to work, the Azoo temperature controller detects the temperature of the water actually in the tank and then turns the power to the in-line heaters on and off as needed to maintain the desired water temperature.

This tank is my first time ever working with in-line heaters, and I have been a big fan so far (when used in conjunction with a temperature controller, anyway). Not only is my water more evenly heated, but the temperature seems to stabilize much more quickly after a water change if I accidentally used chilly water. I do keep two old-fashioned glass thermometers at either end of the tank so I can quickly and easily spot-check the temperature.

I’ve thoroughly enjoyed getting to set up this tank. I loved the engineering and logical challenges it presented, and I’ve been delighted with the final product. In the future I probably won’t use fake rock walls just because they pose such a challenge when placing equipment in the tank, but I have to admit it does look pretty awesome.



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