Hi Everyone

Hello.
Newbie here looking forward to all your shared knowledge and experience to help me become a good fish keeper, hopefully 

Yes, I've bought the Marina lux led 38 litre kit. I've also bought a small sponge filter and air pump with air stones. I'm in the UK and am looking at keeping nano fish. Got my eye on Dwarf Corys and Chili Rasboras with a few shrimp. I have used Tetra complete substrate with a 3-4mm gravel cap about an inch thick. Got plants including Valisneria, dwarf grass, java fern and another couple of varieties I cannot say or spell    I've also got some driftwood coming this week.
I filled the tank with Cl treated water yesterday and am thinking of using Fluval cycle to kick things off as it was recommended by my local fish shop.

That substrate seems to be OK, I can't find any references to it leaching ammonia for months.

The first thing you need to find out is how hard is your water. The fish you mention need soft water so if you have hard water you'll need to rethink the fish. Your hardness should be somewhere on your water company's website, though some do make it tricky to find - if you can't find yours, tell us the name of the company and we'll see if we can find the page. When you have the hardness, please post the number here, and the unit of measurement as there are half a dozen units they could use - it's worse than inches/cm!
If your water is suitable, bear in mind that both the fish you mention need to be kept in large groups, so at least 10 of each.

The gravel cap - how large are the particles, and are they rough or smooth? Cories prefer sand so they can take a mouthful of it and sift through the sand eating bits of food caught in it, and then expel the sand through their gills. They can't do this with gravel. But if the gravel particles are fairly small and smooth there shouldn't be a problem; it's sharp gravel which can cut their mouths allowing infections to take hold. With gravel, the food falls between the particles and can rot there if too much food is fed to the fish, and this rotting food is the source of the infections.
So smooth gravel and not over feeding is fine; rough gravel and feeding way too much is not good. Fish need a lot less food than you'd think. Mammals like us use most of our food to maintain our body temperature while fish get their temperature from the water.




Then you need to cycle the tank. Since you plan on having plants, you could do a plant or silent cycle. With this method, the tank is heavily planted with fast growing plants, then we wait till we a certain they are growing and not about to die. The easiest way to do this is to take a photo of the newly planted tank so there's something to compare the plants to a couple of weeks later.
Once the plants are actively growing, the first batch of fish can be put in the tank, and it is sensible to test every day for ammonia and nitrite. If they stay at zero for a week, the next batch of fish can be added. If they read above zero, a water change needs to be done to get the levels down to zero.
@Matt should be able to help selecting plants suitable for your tanks size.

All good from my perspective - not sure on the hardness though but will try and check later on for you. The plants are good too. One exception is the microsorum. This can’t be planted but need to be tied to a rock/ piece of wood - the rhizome especially needs to be in the water not under gravel etc as it will rot

Yes, that's lovely soft water very suitable for chili rasboras and dwarf cories 

The unit is degrees Clark. Fishkeeping uses dH (aka German degrees) and ppm. You'll find fish profiles use one or other of those two.
1.8 deg Clark = 1.4 dH and 26 ppm.




I am so jealous - the image says "Wigan north west" so you are close to Pier Aquatics in Wigan. I used to live in Lowton before I started keeping fish, I'd never be out of there if we still lived locally 

Looking at the image of the water quality I see your nitrate is very low, which is good. It is now known that nitrate above 20 ppm has long term effects on fish, and you should have no trouble keeping it well below 20 ppm. My tap water nitrate is similar and my tanks both test at zero for nitrate because of the plants in there taking up all the ammonia made by the fish so there's none left to be turned into nitrate.



It's a long time since I was in Pier - we called in when visiting my mother, and she came to live with us in 2011 so it was before that. I just remember all those tanks, many with fish I'd never seen before.

Water changes do take out nitrate - if there are any. When tap nitrate is low, the tank has live plants, the tank not grossly overstocked and the fish not heavily over fed there won't be much nitrate being made in a tank.

Plants prefer ammonia as their source of nitrogen, and they turn it into protein rather than nitrite. If there's insufficient ammonia, they will use nitrate but they have to turn it back to ammonia to assimilate it which takes energy. But if a tank is very overstocked, and/or the fish keeper feeds far too much, there will probably be more ammonia made in the tank than the plants can cope with, in which case nitrate rises in the tank.
And where a tank has no live plants, all the ammonia made by the fish is turned into nitrite them nitrate by the filter bacteria.


Water changes still need to be done even with zero nitrate, especially with water as soft as yours.
Minerals in the water are used up by fish and plants; water changes replenish them.
Fish excrete more than just ammonia - other waste products, hormones etc. Water changes remove these.
Very soft water usually goes hand in hand with low KH. KH is a buffer which prevents pH changing. If there is not much KH it can get used up leaving nothing to stop the pH dropping and suddenly changing pH is not good for fish. Regular large weekly water changes top up KH.

Hagen's website won't load, something to do with its certificate, so I can't access the manual 

Sponge is better than bioballs, ceramic noodles etc as it does both mechanical and biological filtration. You can use any sponge designed to allow water to flow through, cut down to fill the space.
The plastic screen, is that what the call the bio-screen? That could be of some use, though carbon is not needed on a routine basis.

You mean those things which look like flat balls of knitted plastic? Yes, many people use those. Basically anything which biofilm can grow on is OK in a filter; the filter bacteria live in the biofilm. The thing to look for is "contains surfactant/detergent" on the label and don't get those.

That flat thing with holes is the bioscreen, designed for bacteria to grow on. Since it's flat it won't grow as many bacteria as other types of medium since sponges have a huge surface area (the inside of all the 'bubbles' and other media are designed to have a large surface area for the volume.

I've also found a description of the cartridge:
"helps remove pollutants and odours, removes toxic ammonia and captures floating debris".
I don't like that phrase "removes toxic ammonia", that sounds like it contains zeolite. Zeolite absorbs ammonia, leaving little or none to feed the bacteria. Then the zeolite gets full and stops absorbing ammonia which then builds up in the water as there are insufficient bacteria to remove it. The fish keeper is tied in to replacing the cartridge before the zeolite gets full, for ever.

With live plants in the tank, the zeolite issue isn't quite as important. But the cartridge also contains carbon (the removes pollutants and odours bit) which adsorbs plant fertiliser.

I would take the cartridge out now and replace it with better media of your choice.

My son uses Temu 

Read the packaging carefully on those sponge + green things as many of them are impregnated with detergent (surfactant is another word for detergent). Also, they may be the type of sponge designed to hold water like a bath sponge rather than allow water to pass through it - filters need the type where water flows through, ie reticulated sponge/foam.
If these turn out the be the 'holding water' type, you need a different sponge. Any brand of filter media would be OK, just buy something slightly bigger than you need and cut it down to fit.