Diatoms in naturally lit tank

[James Turner]

Hi all,

I've had a look through the threads and all of the diatom posts related to a tank with LEDs. My tank doesn't have lights and is lit by natural sunlight.

The brown diatoms are starting to take over the tank. It's a newly set up tank (about a month and half ago). Could I get some advice on how to handle this please?

More about the tank - 33L, cold water, natural lit (but only indirect sunlight), mostly fake plants but I have salvania plants on the surface and one moss ball in the tank.

At the moment I have 3 danios in there as I'm not convinced the tank has finished the nitrogen cycle (im paying attention to the water readings. Ammonia still reading, small nitrite reading starting to happen).

I read that nerite snails are good so I put two in the tank today, they are very small. I also put in a black Cordoba sucker fish (I know ive messed up the name of that fish), as the lady in the store said they are good at eating diatoms/algae.

Is the natural light causing the diatoms? I don't think I am overfeeding the fish, I feed them sprinkles at a time and wait for the danio to eat all the flakes before I give more so no waste sinks to the bottom.

I have taken the ornaments in the tank out and scrubbed the diatoms off but I think I might be scrubbing away the good bacteria too.

Any advice on how to get rid of the diatoms would be appreciated.

Thank you!
James

 

[Byron]

First, to confirm diatoms and not another type of algae...if the brown easily comes off with your fingertips, it is diatoms. If not, another algae. Your fingertips will not dislodge the bacteria that are very sticky and adhere well to surfaces under water; but any form of brush scrubbing could.

Assuming diatoms...this is normal in many newly set-up tanks as the water is still going through significant chemistry changes. The fact that you are relying on natural light is however probably going to cause diatoms anyway. Algae is normal in any aquarium, and cannot be "prevented" without destroying the biological system. Nutrients will obviously be present (even without fish, organics in the tap water are more than many realize) and the light will basically determine what algae is likely to appear. Live plants will use the light and nutrients (provided these are in balance for the plant species and numbers) and keep algae minimal. Without overhead tank lighting however, live plants are going to struggle. I have never known Salvinia to thrive without overhead lighting, though it might if the tank were in front of a bright window; but then other algae including cyanobacteria (not a true algae) would likely be problematic. It was for me when I tried this.

Fish that eat algae are very specific in what algae they will and will not eat. Otocinclus, Farlowella (Twig Catfish), Bristlenose pleco (to name three common species) will eat common green algae and diatoms, but not touch "problem" algae like brush, beard, etc. Fish like the often-sold Chinese Algae Eater are worse than useless and bring with them considerable other issues. But acquiring fish to solve a problem is never a wise move, as all fish have specific requirements and may be unsuitable for one or more various reasons. [I've no idea what "Cordoba" might actually be.] The only safe method is to pin down the algae, then try to resolve the causes.

Snails are good algae eaters, by which I mean they readily eat algae, but they will almost never deal with a problem algae. I have the small snails (Malaysian Livebearing, and common pond) in all my tanks, and they eat algae from all surfaces, but can never handle a problem outbreak of say brush algae.

As explained above, the diatoms may disappear as the biological system establishes, or they may persist because conditions are to their liking.

 

[James Turner]

Thanks for replying.

Yes I think it is diatoms as they do come off very easily when I swipe my finger. I have read it does go away once the tank is established. I hope so! For now I'll keep an eye on it and clean when the tank when it gets too much. I've read it shouldn't harm the fish.

The Cordoba fish is a corydora... I just couldn't remember the name earlier. The snails and the corydora do appear to be eating the diatoms but yes, I would rather address the route cause which I think from your post might be the natural sunlight. It sounds like I'll just have to let the diatoms run their course while the tank settles.

It is quite bright where the tank is, it's under a window but doesn't get direct natural sunlight so I'll see how the salvinia get on. It's more of an experiment more than anything. The danio seen to like it.

Thanks for reassuring me that the diatoms are normal at this stage.

 

[Byron]

Agree. Just a correction on the Corydoras, none of these will eat any algae. They are grazers and will graze every surface in the tank, looking for tidbits of food. But they do not eat algae.

 

[James Turner]

Oh! Sounds like I was mis-sold the Cory!

Do you think I should make sure some of the food floats to the bottom for the corydora then?

 

[Byron]

Oh! Sounds like I was mis-sold the Cory!

Do you think I should make sure some of the food floats to the bottom for the corydora then?

This will not work, you must have proper sinking food for catfish, like shrimp pellets, etc. But aside from that, there are some issues here.

Cories must have a group, at least five. This is only a 33 liter (8 gallon) tank, so this is an issue. I don't know which cory species, but most get 1.5 to 2 inches, unless you got one of the dwarf species like the pygmy cory. What are the tank dimensions? Though I am not hopeful cories will work here regardless, except for the pygmy species if you have sand; otherwise the one should go back...explain to the store.

What exactly do you mean by "cold water" tank? If room temperature, what temperature range are you looking at (day/night, seasonal)? Or if you just meant cooler than warm tropical, say low to mid 70's F, confirm.

Now that I am on the tank size and temp, what are the danios? Are they intended to be permanent? What fish are intended for this tank?

 

[James Turner]

Hi Byron,

These were all questions I asked the staff at the store (pets at home) regarding the cory and she told me the opposite of what you have just said.

Perhaps I should just take it back. I'm not experienced with keeping fish and don't want to harm it.

When I say cold water I mean I don't have a heater in the tank so it will be at room temperature.

On dimensions of the tank I'm not sure, but it is long as I know danios like to swim the length of it. Pets at home do a points system with tanks which relates to how many fish you can keep in it depending on their size and how taxing they are on the environment of the tank. I'm sticking well below the maximum point allowance.

I intend to keep the danios permanently, I'm not using them just to cycle the tank. I'll probably get a couple more once it's cycled.

 

[Byron]

Another store with inaccurate/misleading information. There have been many threads on this forum with similar. Ignore the "points system," sounds completely unreliable. Very briefly, a shoaling species (like tetras, danios, rasboras, barbs, cories, and some other groups) must have a group. Tank size factors in to this, but there must be several of the species or they will be stressed and this leads to health issues, possible aggression, premature death. Species vary, as do minimum numbers. Your three danios for example need a few more, but we need more info to sort this out better.

For the dimensions, measure the tank on the outside for the length (side to side along the front), width (front to back along the side) and height (depth). Inches or cm, either.

Can you pin down the danio species? Are they Zebra Danio?

Temperature will work for many (but not all) tropical fish, provided the coldest (at night during winter presumably) is not lower than the high 60's F.

 

[seangee]

Sadly pets at home is not a place I would go to for advice on fish. They are a chain store who keep fish as an after thought and in my experience the staff know very little about fish. They are judged by their abllity to sell stuff rather than what they know.

Many danios should be ok at room temperature provided the room is always kept above 18C, but for most tropical fish you do need a heater as they do best in the 24-26C range. Danios are active swimmers so probably need a tank of at least 90cm long. There are different types of danio so if you know the species please let us know and we can advise (or post a photo).

There is a lot of useful info and links on the page at http://www.fishforums.net/threads/beginners-resource-center.277264/

I agree with all of what Byron has said but strongly suggest that you read through the info in the link

 

[James Turner]

Thanks guys, I'm really disappointed with pets at home - I thought I was doing all the right things!

I have the dimensions of the tank - 33.8 X 29 X 33.8 cm. If this is too small for what I have please let me know and I'll try to rehome them. It sounds like it's definitely too small for the Cory. Could you suggest some fish that are suitable? Betta perhaps?

The danio are 2 pearl danio and 1 leopard print. All about 1.5cm long.

Can I ask something else on stocking? Should I pay much attention to the 1 inch per litre rule?

 

[Essjay]

I once read a comment by a fish keeper who worked for Pets@Home and the person said that as a fishkeeper he was sent to work in the dog department while someone who knew nothing about fish was sent to the fish department. They just work from a script - how big is your tank etc.

The rule is 1 inch of fish per American gallon, with the fish being thin torpedo shaped fish under 3 inches long, adult size. It doesn't apply to deep bodied fish or fish longer than 3 inches. And while it is a good rule to stop newcomers going mad and overstocking a tank, there is a lot more to stocking a tank that just the number of inches per gallon.
As you have discovered, your danios may fit according to the 'rule' but they need a much longer tank because of being such fast swimmers. And danios are shoaling fish which need at least 6 of the same species. Pearl danios and leopard danios are different species, leopards are a colour variation of zebra danios.


Bettas are indeed suitable for the tank, one male or one female. I have a nerite snail with mine, nothing else, so your two snails will be fine. But you will need a heater as bettas like it slightly warmer than most tropical fish.

 

[James Turner]

I'm really glad I came on here.

I went to a specialist fish place after work and described the tank and fish in it and he told me thst all the fish are unsuitable and agreed to take them off me and rehome them. He mentioned Betta or guppy might be suitable. He asked for photos of the tank. So that's what im going to do. Give the fish to him then see what he suggests as the best fish for the tank.

He also said pets at home will tell you anything to get a sale.

 

[Byron]

Agree. I would return the danio, this is not going to be in the best interest of the fish otherwise.

EDIT: Your post #12 appeared while I was typing. Before jumping into a Betta, let's sort out the GH, pH and temp issues, as you may have other or better options. A tanks of 20 small fish, two or three species, might be more interesting for you than a single Betta. Your decision, but let's know your options first.

Possible fish...now we have two issues to resolve before we can consider species. First is temperature; temperate water (= cold water for our purposes) will be much more important for small fish which are the sort that suit this sized tank. The smaller the fish, the higher the metabolic rate, and temperature drives this.

Second is GH and pH. GH is general or total hardness, which is the level of dissolved minerals especially calcium and magnesium in the water. If you are on city water, check the website of the water authority, it may post this data. Give us the number and their unit of measurement (there are several). They may also have the normal pH, which is also important though somewhat less so, and it can vary in an aquarium depending upon the GH and some other factors I needn't get into now.

A Betta was mentioned, but this needs warmth; GH and pH are somewhat important but probably not an issue unless they turn out to be extreme.

There are many small sized species that would work in the tank as far as tank size is concerned; we just need to pin down the GH and pH, as most of these will be wild caught and more particular.

 

[seangee]

@Byron is right and if we know the hardness of your water will be able to discuss options. And betta would restrict you to a single fish. Something you may want to keep as an option is shrimp. I only recently discovered how fascinating they are to keep and observe in their own right. Your tank can accomodate a good number of shrimp and, depending on the species, you may only have to buy a few to end up with a lot . (My original colony of 7 in a 50 litre is now over 100 strong after less than 6 months).

 

[James Turner]

Hello,

I've got a PH of 7 and GH of 9.

Would minnows be a good option? Now that the tank is empty I think I am going to wait for it to cycle before putting anything else in so now is a great time to discuss options I think.

Thanks both for your help!