Fluval Flex 57Litre - Substrate Advice

Hi all

Im looking to buy the above tank for my 4 year old. From reading round a bit I understand the flow issues and various things like the filter intake sucking in fish at the back but these can be overcome and its just about the right size for us and for the boy - it woud look great in his room
specially with the lights - would even like to try phillips hue lightstrip in there to be honest but not looked at that

Im not planning on putting too much in it at all to start with just a few neon tetras maybe

What Im not sure on is the substrate. I understand that planted tanks are better for fish and water quality but the issue I have is with the substrate

I love the look of the bright white sand that you can get but I assume thats no good for the plants - would that be correct??

As we are thinking of getting the white fluval flex I may get the black sand - if thats suitable for plants that is??

Just looking for tips on the right substrate really and any recommended plants that wont grow like mad!

We ae planning on planting and leaving the tank or a month for the plants to establish before we start to stock slowly

Any other tips would be great - its kinda complicated once you start reading up!

Thanks all

Welcome to TFF.

I'll answer your substrate questions, then move on to some general issues. Let me begin by saying that freshwater fish have evolved to function best in a very specific environment, which includes water parameters and the habitat itself (substrate, wood, rock, leaves, branches, plants). So providing what the fish "expect" goes a long way to keeping them alive and healthy.

Sand is an ideal substrate, both for plants and fish. You may at some point consider substrate fish and sand can be the only suitable substrate depending upon the fish species. I'm thinking of one of the dwarf species of Corydoras with a group of neon tetra for example. Sand is essential here, and it will work for any fish you might consider for a 57 liter (15 gallon) aquarium.

White sand is not good for fish. No tropical freshwater fish lives over a white substrate, so that causes stress, and stress weakens fish--stress is the direct cause of about 95% of all fish disease problems. It will also "wash out" fish colours, due to the effect it has on them. And some will do everything to avoid being out in the open above white. Fish expect a darker substrate. As sand is so good, you could get a bag of play sand. Or there are some aquarium sands that will be considerably more expensive. I use gray toned play sand in all my tanks.

Plants are a good thing, but here we need to know the light specifications, as not all light can grow plants well if at all. Light also impact fish; most forest fish come from dim waters, and overhead lighting can be problematical if it is too bright. Floating plants usually solve this, plus they provide a natural cover for fish. One very authentic aquascape for fish like neons would be lots of wood and branches, dried leaves, darkish sand, and floating plants. Floating plants are easiest to keep healthy.

Thats brilliant knowledge - many thanks for the advice - the tank has 7500K LEDs
OK the white sand totally sounds like a no then so black sand as an alternative would be OK? I just like the contast mainly as its a white tank - against the black sand I personally think that looks good.

I honestly didnt know you could just plant in sand I thought you had to have the plant specifc substrate and most of those that Ive seen so far are like a browny earthy look to em which I dont like

Thanks again - amazing

kiteboy said:

Thats brilliant knowledge - many thanks for the advice - the tank has 7500K LEDs
OK the white sand totally sounds like a no then so black sand as an alternative would be OK? I just like the contast mainly as its a white tank - against the black sand I personally think that looks good.

I honestly didnt know you could just plant in sand I thought you had to have the plant specifc substrate and most of those that Ive seen so far are like a browny earthy look to em which I dont like

Thanks again - amazing

Click to expand...

Can you explain the "white tank" for me? I looked this tank up and the photos show a black background, some with a white stand but the tank is black. I'm not sure I know what you're meaning here.

Black sand is OK, though I must say that the one time I used black I did not like it. First, under water and the tank lighting, it was not black but a darkish gray, and it showed every spec of stuff, something I never see with play sand. If you do get an aquarium sand in black, make sure it is completely inert. Some aquarium sands will increase the hardness and pH and this can be serious for fish.

Which brings me to something I forgot earlier...the parameters of your source water. GH (general or total hardness), KH (carbonate hardness or Alkalinity) and pH. You should be able to ascertain these from your water authority if you are on municipal water (as opposed to a private well). Small fish suited to this small a tank will likely be wild caught, and attention to parameters is critical. Fish that suit your water will be much easier than going down the difficult road of adjusting water for fussy fish.

If the light is 7500K (not 6500K ?) that is a tad on the blue (cool) side, and may be lacking sufficient red for plants. We can explore this further.

Plants do not need special substrates. Nutrients occur from water changes, fish feeding, and if needed can be added as substrate tabs or liquid fertilizer. Different plants have differing requirements when it comes to nutrients.

I'm in the process of setting up a 57l Flex. The lights will be adequate for plants described as easy or moderate care. You can also adjust the colour temp using the remote (although you would have to figure out how to measure the combination you have created).

If you are in the UK Argos play sand is dead cheap and does a great job as a light substrate. For the Flex I have chosen Limpopo black sand, which as Byron points out isn't really black. Both of these sands are inert and provide no nutrients for plants. I will be using grow tabs in mine. These are literally fertiliser tablets that you place under the roots of your plants, they take 2-3 months to dissolve.

Here is a very early pic (no plants yet)

If your tank came with the grill covers seen in my pic that will be adequate for the fish you mentioned. For smaller fish or fry you could put a piece of fine sponge between the cover and the vents in the tank. Alternatively some filter sponge attached to the inside of the vents.

FWIW the flow is not too high for the fish you mentioned. I aimed one of my nozzles into the back corner, slightly upward, and the second at the side wall so that it flows above the surface - but doesn't actually shoot out above the surface (hope that made sense).

Fish feel happier with dark gravel and their colours will contrast better in a tank with a dark background and substrate. If you can find a dark gravel (brown, black, whatever you like) it will be fine for fish and plants.
If you want bottom dwelling fishes then try to find a smooth gravel or sand, rather than gravel with corners and shape edges.

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You can grow plants in the gravel or put them in pots. I like pots because you can move them around and redecorate without disturbing the plants. Simply pick the pot up and move it.
I use a 1 litre plastic icecream container and put about 20mm of gravel in the bottom. Then I put a thin layer of normal plant fertiliser on that gravel. Then I cover the fertiliser with about 5mm of red/ orange clay that has been dried and crushed into a powder. Then fill the container with gravel.
The plant gets planted into the top layer of gravel and when its roots hit the fertiliser and clay, it takes off. The clay stops the fertiliser leaching into the water.
You can smear some glass silicon (glue) onto the outside of the plastic container and stick gravel to it so it is less noticeable. Or put a rock or driftwood in front of the pots. Or you can just let algae grow on the pot.

You can add liquid plant fertiliser to the tank if you like but it isn't necessary. I like Sera Florena because it is an iron based fertiliser and is relatively safe for fish and other aquatic organisms. You add a bit several times a week and it helps the plants do a bit better. But it is not essential.

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re: the tank. I personally do not like tanks with curved glass because if it is damaged you have to buy a new tank. Curved glass is weaker than flat glass and whilst it can look interesting, it really isn't the best for fish keeping. Curved glass also makes it harder to treat fish if they get sick because it is harder to work out the volume of water in the tank, and you have to guesstimate how much water is there. However, if you want a tank with curved glass, then get one.

Personally I would rather a standard rectangular tank. It is cheaper and easier to work out water volumes

Thanks all - that a briliant help

The black fluval flex does also come in white too - just suits the boys room better - I like the black one too though

https://goo.gl/3Uy6HS

I understand the downsides of these designer tanks and I know biggger is better but for us I think it suits for now
Ive heared other parents stories about fish and that it was a waste of time (kids lost interest) after a few months so if that does happen I will probably move it elsewhere in the house and want it to look good

Thanks everyone - been a great help for a complete novice

I also havve plenty of the play sand in the grandparents garden all covered in a container so that will maybe a cheap option (its really fine grain size though)

kiteboy said:

Thanks all - that a briliant help

The black fluval flex does also come in white too - just suits the boys room better - I like the black one too though

https://goo.gl/3Uy6HS

I understand the downsides of these designer tanks and I know biggger is better but for us I think it suits for now
Ive heared other parents stories about fish and that it was a waste of time (kids lost interest) after a few months so if that does happen I will probably move it elsewhere in the house and want it to look good

Thanks everyone - been a great help for a complete novice

I also havve plenty of the play sand in the grandparents garden all covered in a container so that will maybe a cheap option (its really fine grain size though)

Click to expand...

Hard to tell from the photo at that link, but you do not want a white background. Black is best, in a dull finish. I use black construction paper taped to the outside rear wall of my tanks. It increases the visual space, and the colours of fish and plants show up better. And, again, fish will be more relaxed, they do not like white or reflecting surfaces.

As for the fine play sand, that is OK. Play sand is pretty much the same wherever. Just don't have it too deep, about 1.5 to 2 inches depth overall (meaning when level in the tank before you aquascape it) is adequate.

The white background is actually a partition inside the tank which separates the filter section from the main section. I'm not sure if that can be altered?

I'm pretty sure the back section is glued in and cannot be changed, but you can silicon some plastic aquarium backing inside the tank and that will cover it up. Get an aquarium backing from the petshop and use some glass silicon to stick it to the inside of the tank on the back panel. Just smear a thin layer of silicon around the edges and stick the picture on. Let it dry for a couple of days then set the tank up.

If you don't want to do that you can silicon plastic plant leaves to the back, or you can look for the rubber backings that go inside aquariums and silicon one of those in.

I have the white version of this tank amd i love the white contrast on the plants and fish also if you are looking for a white or black substrate i use white gravel and sand with some white rocks for the amazon swords with some plant soil under it then i have used fluval stratum at the front that is black realy good for plants

Its hard to see for the plants so i have put a pic from when i set it up

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