Help! Tank Suddenly Full Of Algae.

Hi, I'm very new to fish keeping. I got a 40L tank 5 weeks ago. I ran it for 1 week and then added 2 plants. Then after 2 weeks I added 5 neon tetras and 2 cory catfish. Everything seemed fine. After 3 weeks I added 3 small snails. After 4 weeks I changed the filter and did about a 20% water change and cleaned the sides and gravel.

Now a week after the water change the algae levels have suddenly gone crazy in the last few days and the tank isn't smelling too good! Fish still seem fine and I've done a dip test thing and levels are good according to the leaflet enclosed!

So is this normal? And can I do anything as I really don't want a cloudy, smelly fish tank

Thanks, Emz x

Hi, welcome to the forum. Sorry it has to be with a problem.

First of all, ignore the algae till you have the answers to some questions.

The first thing to do is a water change, that's always the first response to something odd in the tank. Change at least half the water.


You say you used a dip test, but they don't usually include ammonia. You need to find your ammonia levels asap. It would be best of you could get your own ammonia tester but in the immediate term, take a sample of tank water to a fish shop and ask them to test it for ammonia and make sure they give you the actual number not something like a bit high or fine.
Ammonia is the first thing to go up, and should always be tested for if anything looks a bit iffy which is why I suggest getting your own tester. And it encourages algae to grow.

When you changed the filter, what exactly did you do? Was anything left inside the filter or did you change all of it?
Manufacturers will have you changing the media (the stuff inside the filter) on a regular basis but all this does is make them money. And when you remove the media you are also removing a large portion of the good bacteria the tank needs.
If you tell us what is inside the filter we can tell you what needs changing and what doesn't. The other problem is that some filters for small tanks have media which is next to useless so we can help if that is the case here.


The final problem you have is that the tank is unlikely to be cycled - that means it is unlikely to have grown all the good bacteria it needs yet. And if you have changed all the media you have just removed a lot of the bacteria that have grown.


Don't panic yet. As I said earlier, worry about the algae later, it will probably sort itself out once you've sorted out the other things.

But before anything else, change at least half the water in the tank.
Then tell us about the filter.
Then get the ammonia tested and buy a tester.


Fiona posted while I was typing 

Hello Emz, and welcome to the forum.

Fiona and Sue have covered everything so far..... but I'll just add that the API Freshwater Master test kit is the one that we all tend to use. Your Local Fish Shop should have one in.

Actually, I'll also add that it's best not to ask for advice from your LFS, ask on here 'cos we're very honest and we're not trying to take your money!

Test kit looks like this:

You'll probably find the API kit cheaper to buy on amazon or ebay.

To avoid bias I'd say a LOT of shops will just sell you anything you want, there are however some very good shops, you just need to find one  but yes we just give you honest advice with no ulterior motive and between us I reckon we have a least a century of fishkeeping experience 

Hello everyone 

Thank you so much for your replies

Okay I think I've got all the info needed:

1. the algae is bright green and I can't really describe the smell, just that it's like a tank should smell like but stronger (I can smell is when I'm near the tank whereas before I couldn't)

2. No I didn't use ammonia when cycling the tank.

3. The test strip doesn't have ammonia reading on!
*  It has Nitrate between 0 -20 (the colour on the strip is a bit darker than the 0 reading but less dark as the 20 reading)
* Nitrite at 0
* PH at 7.5
* KH at 80
* GH at between 120 - 180 (again colour is in the middle)

4. I think we have hardish water.

5. The filter is called Aqua Flow 100 and the filter comes off as a whole and the new one clips in. It says on the box that it's 'dual action activated carbon' It has foam around the edges and then these black strips inside. I still have the other filter that I took out!

Hope that's everything answered and I'll do a 50% water change this evening.

Thank you so much again your help is appreciated

Emz

Sorry just seen about the snails. Yes all there, actually I have 4 new ones just spotted today

Yep - snails taught rabbits all they knew about breeding!

Spanks for @ColinB

Emmz did you change your cartridge recently? I've got that filter in my QT, I've had it 2 years and I've never changed the foam, if you do that you loose all your filter bacteria and trigger a cycle, which means the fish waste won't be processed into harmless substances.

Lots of info, thanks Emmzz. And don't worry, you aren't stupid. Anyone would think that the tank manufacturer should know what they are doing but unfortunately, as you are discovering, this isn't actually the case.
At least your filter has sponge, I was afraid it was one of those awful filters with nothing but carbon and zeolite.

I have googled Aqua Flow 100 and it appears to be a Superfish brand. It would appear that you can remove the media from the media box and that is like an outer cube of sponge with carbon granules inside - is that right?

If it is, take the filter box off of the filter, remove the media and empty out the carbon granules. Then try to stuff as much of the old sponge as possible into the hole where the carbon is supposed to be. Cut it up if necessary to make it fit. Provided the old sponge is even a hint of damp the bacteria in it should be OK.
If absolutely necessary, carefully break the outer casing of the changeable box in some way that you can put it back together.
Instead of changing the media, all you need to do now is squeeze the sponge in some of the water you take out when you do a water change - never clean it under the tap or the chlorine in the water will harm the bacteria colonies. Don't scrub the sponge to make it look sparkly new, just enough to get rid of the debris that will collect in it.
You only need to change the sponge when it literally falls apart. They last for years. Maybe not quite decades, but certainly a lot longer than a few months.

Until you know if you have ammonia in the water, and how high it is, you'll need to do a 50% water change every day. But as soon as you know the ammonia level, post it here and we can take it from there.

Nitrite is zero, which is good, though if you do have ammonia you will find that you'll get nitrite before long.
Nitrate depends to a large extent on what is in the water supply. If you test your tap water, that will tell you if the amount in the tank is all from there or if you have some bacteria in the tank turning the ammonia into nitrite and on into nitrate.


And some reading for you. We are assuming that you are stuck with doing a fish-in cycle. This explains what is happening and what you need to do. Sit down with a cup of tea/glass of wine and you'll see what to do.

If the old sponge is still damp, it might be better the other way round now that I've thought about it. The old sponge was in there longer than the new one has been so it should have more bacteria (in theory!). So:
Empty the black granules out of both sponges.
Chop up the new sponge, or whatever is necessary, and put the new sponge into the hollow in the old sponge.

Don't worry if it won't all fit, just get as much as you can in.

And don't wash the sponges just yet. They may be mucky but leave them alone for now. Don't do anything to upset the bacteria you have !

I don't even qualify for a bus pass yet 
















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