Setting Up A New Fish Tank

Setting Up A New Fish Tank

Setting Up A New Fish Tank


This week’s blog will be a little different from usual. A little while ago, I got myself a brand-new fish tank. So we thought that it might be a good opportunity to show how to go about setting up a new tank, transferring/adding fish, and how to deal with some of the more common issues that can crop up. Accompanied with as many pictures as I remembered to take.


First things first, figure out where you ideally want your tank to go. Measure the gap and to ensure that the tank will fit, last thing you want is to get home with a big glass box that doesn’t fit anywhere. Choose somewhere the floor is stable, preferably flat, and capable of taking the weight of the tank you want. Remember 1 litre of water weighs 1Kg; big tanks are better kept on the ground floor. Lastly, while not absolutely crucial, choose a spot out of direct sunlight if you can, it will save a lot of bother in the long run and help prevent your tank getting overrun with algae. 

I had an alcove to the right of my fireplace that was just begging for a fish tank, so the decision making for me was quite easy since the alcove filled all the criteria I’ve listed above. So the only decision for me was which tank to get, me being me, wanted to go for as large a volume of water as I could fit, which led me to opt for the Fluval Shaker 345. Not as wide as you’d expect for a tank of that volume, it makes up for it in height and depth. Was a bit of a snug fit as you can see. And most importantly (so I’m told) it matched the furniture. 


Another reason I went for the Fluval Shaker, aside from it fitting perfectly, was the equipment that it comes with. You might’ve spotted on the pictures that there are two caps in the back right of the tank, that’s because the tank is drilled; meaning that the pipework comes right up through the bottom rather than having to go up and over. Looks a lot nicer in my opinion. It comes with a Fluval 407 external filter, which is a decent bit of kit and certainly better than my last filter. Two of Fluval’s Aqua sky Bluetooth LED light bars, fully programmable, nice and bright with a good spectrum for plants. It also comes with a 300-watt internal heater, but I chose not to use it and opted for an AquaEL 500-watt external heater fitted to the return pipe instead. I wanted to avoid equipment being on show as much as possible. When it comes to heaters you want at least 1 watt per litre of water. If your heater’s not powerful enough, you’ll find that it is running constantly to keep the water at the right temperature and will end up being more costly than running a more powerful heater which would only need to come on briefly. Also notice how I ensured that the plugs were up off the bottom of the cabinet in case of any leaks, shouldn’t need me to tell you water and electricity is a no-no. 

We’re going to jump forwards a little bit here. Since I was transferring over stock from a previous tank, I didn’t start my filter from scratch, I took the already active bio-media from my old filter and put it into my new one. I didn’t do this until it was time to move my fish, but we’ll talk about it here since we’re already on the filter. Also, I did forget to take pictures as I was putting it together, so these were taken a few weeks afterwards which is why the filter doesn’t look as clean as it could’ve. 

As I mentioned previously, the 407 is a good filter; but it can be improved. It comes with a section that houses some larger strips of corrugated sponge (a good design for sponges, do try to use corrugated sponge if you can. It gives it a larger surface area making it more effective), and four filter baskets, one with sponges, one with bio-media (the white hula hoop looking ones) and two with bags of activated carbon. That’s not enough bio-media for my liking, so I filled two and a half of the baskets with my old bio-media plus the new stuff, kept the sponges the same and put two of the four bags of carbon on top of the half-filled basket keeping the others for later.


Now then, the fun bit, and the bit that’s the hardest to give advice about. We get asked in the shop a lot about what we recommend in terms of decoration and to be perfectly honest, there’s no wrong answer, it’s completely up to you and what you like. That being said, there are some things to keep in mind when deciding what to go with.

Many species would like a cave or crevice they can hide in and claim as their own little space in the tank, it makes them feel more secure. A darker substrate can also help them feel less exposed, prompting them to show off their colours a bit more brightly. Anyone who’s been in the shop and had a good look at our show tank can see the benefits of a darker substrate. 

Keep taller decorations to the back and sides and shorter ones to the front, try not to obstruct your view of the tank. Don’t overfill the space to the point that there’s not much open swimming space left, but if it’s too barren it can leave the fish feeling exposed. 

Are you going to use live plants? They need looking after too. Some species of live plant can be quite demanding and require special lights, substrates, and addition of minerals and fertilisers. While others can do quite well with minimal effort. Do the fish you want go well with plants? African cichlids for example are quite often kept in tanks with no plants because they have a habit of digging them up and/or eating them.

I had a basic plan in my head of what I wanted my tank to look like. Black background, two large pieces of branched wood in the back corners surrounded by rocks and live plants, then a large open area at the front with natural sand and some carpeting plants around the edges. And I’m happy with how it turned out.

First thing I did was choose the wood and rocks. I measured the wood at the shop to ensure that it would fit. Then decided which way around I wanted them in the tank.

Once I was happy with the wood, I cleaned the rocks and positioned them along with the wood and built up a layer of Seachem’s Flourite plant substrate, holding them in position.

Next was a layer of natural sand at the front of the tank and covering the Flourite in front of the rocks. The small gap between the rocks on the left-hand side turned out to be a mistake. The Flourite was constantly knocked down through the gap on to the sand by my fish.

The first lot of plants came next after removing them from their pots and separating them into smaller cuttings. A bulb of Crinum in the centre of the left piece of wood. Broadleaf Amazon Sword in the back right. Micranthemum Monte Carlo in the back centre, and a bit around the wood. Then Narrow Sword Grass in front of the rocks. And finally, Peacock Moss attached to the branches of the wood.

I’m going to take the opportunity now to talk about wood. Normally when people buy wood from the shop, we’d recommend weighing it down for a while to make sure it doesn’t float when the tank gets filled up. But apparently, I don’t listen to my own advice and didn’t do that. Luckily the rocks and the weight of the substrate held them in position. That could’ve been a nightmare to fix. Aside from floating two other things tend to happen when you use wood in a fish tank. One of which is the release of tannic acid/tannins. Sounds worse than it is, promise. Tannic acid makes the water look brown, like someone’s left a few teabags in the tank and can lower the pH ever so slightly. And that’s about it; it’s harmless and will fade over time and with water changes. Although, some aquascapers do keep their tanks with high tannins to recreate wild habitats more closely. Different woods will contain different amounts so it will be variable in how long it takes to clear up. I was lucky and the wood I used barely contained any at all. For comparison the show tank at the shop went so brown you couldn’t see from one side to the other. If you want it gone sooner rather than later; using products like activated carbon and Seachem’s Purigen will absorb the tannins and clear the water. Using the shops show tank as an example again, we put a sachet of Purigen in the filter and it was clear within a day. 

The other thing that will happen when using wood is a biofilm coating the wood. This is a growth of bacteria and fungi developing on the surface of the wood to process/eat the natural sugars that can be found there. This looks unpleasant but once again is harmless and goes away in time Some fish will eat the biofilm but scrubbing it off with a brush works well. I just left it alone.

As you’ll see in upcoming pictures, the plants in my tank changed a fair bit between set up and now. The Micranthemum Monte Carlo, and Narrow Sword Grass didn’t do as well as I’d hoped. It’s quite a tall tank and the light was not bright enough for these two plants by the time it reached the bottom. You may also notice some Japanese Cress that came and went; something nibbled the bottom of them. But what you’ll see in the final image is how the tank looks now. I have replaced the Monte Carlo and Sword Grass with Crypt parva and lots of it, a lovely little carpet plant that isn’t as demanding when it comes to light, added a lot more Broadleaf Amazon Sword and a tall plant in the back centre called Giant Vallis. I also added one more rock to plug that gap on the left. Fantastic decision if I do say so myself.

Adding Livestock

The moment you’ve been waiting for since you first decided to get a tank, adding the fish. As I’ve mentioned my tank is an upgrade, I already had a tank with fish. For me it was as simple as transferring the filter, which I covered earlier, then acclimatising and putting the fish in all at once, not much to talk about. So, let’s go over it as if it was all brand new.

Before adding any fish to a new tank make sure that it’s all set up and running first, let it run for at least a day or so after filling it up to make sure that the equipment is working and to give it time to get up to temperature if it’s a tropical tank. You should also check the pH of the water at this point. The pH of your water depends on where you are in the country if you’re using tap water. Up here in the North we have soft acidic water, so we often have to put some buffer into our tanks and ponds to bring the pH up to what it should be. Not a problem you usually get down South, the trade-off is they have to de-scale their kettles and shower heads because of all the minerals in the water.

After making sure everything’s okay you can add the first lot of fish. Start by floating the bag in the water still sealed for 10-15 minutes. This allows the temperature in the bag to slowly match the tank, so they don’t get a shock from sudden change of temperature. Next open the bag up and let some of the tank water into the bag without letting the fish out, leave them like this for about 10 minutes. This allows the fish to gradually get used to any change in water chemistry between the tank water and water in the bag. This is usually enough for the first additions since nothing much will be going on with the tanks water just yet, but subsequent additions should be mixed another 2-3 times each with a 10-minute wait in between. Once the first fish are in the nitrogen cycle starts up, I’m not going to go into great detail about that here since it deserves its own dedicated blog post. But the important bit to know now is that ammonia will begin to build up in the tank then fall followed by a build up and fall of nitrite, once both are gone it is safe to add more fish.

It’s best to add fish to the tank in batches, since the filter in the tank is brand new and won’t have any of the bacteria needed to process the fish’s waste. If you put too many in all at once the ammonia and nitrite can build up too quickly and harm the fish. Ideally test the water every week or so to check how it’s coming along and if it’s safe to add any more fish yet.

You’ll likely notice the water in the tank becoming cloudy shortly after the first lot of fish go in. This is due to a bacterial bloom; you may have spotted a running theme of things sounding worse than they are. Once again, it’s completely harmless. A bacterial bloom like this is caused by the filter bacteria growing rapidly in response to the high concentration of waste that will be building up in the water. Peoples first response is often to do a partial water change, this is unnecessary and will just slow the process down. All you need do is wait; once the waste has been processed the bacteria will die back and the water will become clear again.

Something we get asked about a lot is how many fish you can have in any given tank. Unfortunately, there is no easy answer to this. Just a couple of factors you should consider:

The first limiting factor will usually be the filter. Can the filter handle the number of fish that you want? Is it big enough for the tank? Adding more bio-media will improve its capabilities, but don’t put too much in, to the point that water doesn’t flow though it properly anymore.

Second is the volume of water, not to be confused with the size of the tank. This one tends to cause confusion, yes, a fish will physically fit in the tank, but will the volume of water be enough to cope with the fish waste. Goldfish often cause some upset with this as they produce a lot of waste for their size; meaning they need larger volumes of water and bigger filters than most expect.

Finally, the size of the tank. Will the fish physically fit in the tank without being restricted in its movement or too crowded? Don’t forget to account for the growth of the fish if you don’t plan on getting a bigger tank later down the line. Once again Goldfish are a frequent problem for this, as well as Silver Sharks, Clown Loach, and some species of Pleco. All common sights in aquatic shops and start out quite small; but they can grow much bigger than most people expect them to, over a foot in some cases. Make sure you know what you’re getting, and ask the staff if you’re not sure, it’s what we’re here for.

Et voila, you’ve got yourself a lovely fish tank. Now you just have to keep it that way. Another subject deserving of its own blog post. I’ve got plans in my head for a pond. So, I might be back with another of these later down the line. 

Thanks for reading.


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A great article from our member of staff, Nathan with an in-depth look at all the equipment used and the positioning of decoration and planting...well done