General questions

Hi, I'm a bit confused about some plant related things.
"Low light" - what does this mean? Is it the time the light is on each day or the type of light? I have a Fluval Roma 200L, only one of the lights works but it's very bright and looks as though both lights are on. Is this low light? I've always found it confusing.

Co2 - Do most plants need it? How easy is it to set up/use? Is it worth it? Does it pose any risks to the fish/snails/shrimp?

Plant health - what are the usual reasons for plants dying?

Tannins in wood - are they toxic to the fish at all?

Also water changes... how much water should I be changing per week in a 200L tank?

My tank is infested with hundreds of MTS, do they pose any risks to the fish? I find them very helpful as they clean up any leftover stuff at the bottom of the tank as well as dying plants etc. If I got an assassin snail, would it kill all of them or leave a few?

1. Low light plants are plants that are not too fussy about how much light they receive, this can be brightness, duration or colour. If you look at aquatic plant websites these are usually classified as "easy to grow". Lights for high light plants are generally expensive, and many tropical fish come from forests and bright light stresses them.
2. All plants need CO2, but if you stick with the easy plants there is enough in the water without adding any.
3. Plants need a balance of light, CO2 and nutrients - without knowing more details of your plants and tank we can't answer this. Photos might help along with a description of what is going on.
4. Tannins are fine for fish
5. In my 200L tank I change 125l per week. This is around 75% of the actual volume of water. You should really change at least 50% per week, but more is better.

MTS do not pose any risk. If there are too many it is usually an indication that you are overfeeding. Most people do (including me ). If they are unsightly, or you can see lots in the daytime wait till half an hour after the lights go out and scrape them off the walls. I just drop them into a bucket of boiling water. I normally do this once a year towards the end of summer as they reproduce like crazy when the water is warmer. Personally I would not get assassins.

Are you lights LED or fluorescent? If fluorescent the tubes should be replaced annually as they change colour over time. If LED and one strip is gone it may be worth replacing as the colour balance does eventually change as individual chips start to fail. The most obvious symptom is uncontrollable algae or generally unhealthy plants.

The tank in my signature is low light, its actually quite dark in there. I don't add CO2 and only rarely fertiliser. I do buy cheap plants, if they thrive in my tanks they stay - if not they go in the bin (but then I am known to be lazy )

Low light means absolutely nothing . I used to think that meant those plants were like shade loving terrestrial plants . Not so ! Give them a good strong light and remember that water diffuses light and your light isn’t as bright as you think it is .

seangee said:

1. Low light plants are plants that are not too fussy about how much light they receive, this can be brightness, duration or colour. If you look at aquatic plant websites these are usually classified as "easy to grow". Lights for high light plants are generally expensive, and many tropical fish come from forests and bright light stresses them.
2. All plants need CO2, but if you stick with the easy plants there is enough in the water without adding any.
3. Plants need a balance of light, CO2 and nutrients - without knowing more details of your plants and tank we can't answer this. Photos might help along with a description of what is going on.
4. Tannins are fine for fish
5. In my 200L tank I change 125l per week. This is around 75% of the actual volume of water. You should really change at least 50% per week, but more is better.

MTS do not pose any risk. If there are too many it is usually an indication that you are overfeeding. Most people do (including me ). If they are unsightly, or you can see lots in the daytime wait till half an hour after the lights go out and scrape them off the walls. I just drop them into a bucket of boiling water. I normally do this once a year towards the end of summer as they reproduce like crazy when the water is warmer. Personally I would not get assassins.

Are you lights LED or fluorescent? If fluorescent the tubes should be replaced annually as they change colour over time. If LED and one strip is gone it may be worth replacing as the colour balance does eventually change as individual chips start to fail. The most obvious symptom is uncontrollable algae or generally unhealthy plants.

The tank in my signature is low light, its actually quite dark in there. I don't add CO2 and only rarely fertiliser. I do buy cheap plants, if they thrive in my tanks they stay - if not they go in the bin (but then I am known to be lazy )

Click to expand...

Thank you for answering all of my questions! I use the light that came with the tank which I think is LED, I'm not sure where I'd buy another as the tank was second hand and is an older version than the current one (I think its about 7 years old).
Does the light situation mean medium light plants are happy with the same light as low light plants?

Light is interesting. I have some older LEDs and a couple of new ones with a spectrum rated for growing plants. The difference is huge. With my old systems, I didn't do well with quick growing stem plants, which in nature tend to grow in the open where sunlight hits them. Low light plants have always done okay, as plants from shady environments, often under the forest canopy. Some of the tropical streams I've been lucky enough to visit have been dark places, under the canopy of trees. Most had no plants, but in Africa, I saw some of our low light aquarium plants in patches where the sun got through.

Low light plants like Anubias, Cryptocoryne and Bolbitis are expensive, but they do well. Stem plants can add up because they need replacing.

I've never added CO2. All my tanks are unkempt jungles of low and medium light plants. It's a lot like choosing houseplants for the light in your house.

Tannins are excellent for rainforest fish, and in my opinion negative for hard water fish. You get to a point where you stop thinking "fish" and start thinking of individual species, or fish from regions. Water that's good for a cardinal tetra will kill a molly, and vice versa. Tannins don't kill, but they are a source of acidity (they are tannic acids) and fish from alkaline environments tend not to like them. I have soft, acidic tapwater so I welcome tannins for the rainforest fish I can keep with that.

I'm not as good with water changes as @seangee at 75%, but in a 200 ltr, I would change out a minimum of 50 ltr per week. I would probably lean closer to 70-80ltrs. As I'm typing, I know someone out in internet land is making up a system for never changing water - it's a holy grail in the hobby that tends to draw opinionated old men. But consistent water changes have transformed the lives of my fish - they live far longer, look healthier and breed more easily. I grew up in the no water change, balanced aquarium era, and am now a water change diehard, and I see nothing but positives in water changing.

I am a snail hater. But rationally, I have had trouble with Malaysian snails in the past, as when numbers get up there, they die buried and that can challenge the water quality. Too many can mean you are overfeeding a bit, and they are good indicators of that. Beyond that, I see them as pests.

That’s a very good thought that @GaryE came up with . “It’s a lot like choosing houseplants for the light in your house”. Yes , that’s it exactly . You can only have the plants that thrive in your own personal conditions . My African Violets were thriving where I had them and when I moved them they began to slowly decline . The difference was the windows they were facing .

GaryE said:

Low light plants like Anubias, Cryptocoryne and Bolbitis are expensive, but they do well. Stem plants can add up because they need replacing.

Click to expand...

Conversely plants like ambulia and hygrophilia workout very cheap, as they grow you just snip off the tops and replant the cuttings. Within a few months you can have loads from just a few plants. Splitting the rhizomes from anubias also lets you get more for free - but they take longer as they grow slowly.

seangee said:

Conversely plants like ambulia and hygrophilia workout very cheap, as they grow you just snip off the tops and replant the cuttings. Within a few months you can have loads from just a few plants. Splitting the rhizomes from anubias also lets you get more for free - but they take longer as they grow slowly.

Click to expand...

This is helpful, even though I didn't start with the question. I'll hijack some of the results!
Hygrophilia and Ambulia are uncommon in local stores, but they may be worth tracking down. Sometimes the less demanding plants aren't sold because they don't need to be replaced as often - that's my aquarium plant conspiracy theory. I've never tried Ambulia, but I will now. Hygros always tended to get stalky, and take on the palm tree look, but with trimming and good LEDs they may work. I haven't tried them since my lighting was very primitive.
I'm very jealous of the look of your tank, @seangee.

seangee said:

1. Low light plants are plants that are not too fussy about how much light they receive, this can be brightness, duration or colour. If you look at aquatic plant websites these are usually classified as "easy to grow". Lights for high light plants are generally expensive, and many tropical fish come from forests and bright light stresses them.
2. All plants need CO2, but if you stick with the easy plants there is enough in the water without adding any.
3. Plants need a balance of light, CO2 and nutrients - without knowing more details of your plants and tank we can't answer this. Photos might help along with a description of what is going on.
4. Tannins are fine for fish
5. In my 200L tank I change 125l per week. This is around 75% of the actual volume of water. You should really change at least 50% per week, but more is better.

MTS do not pose any risk. If there are too many it is usually an indication that you are overfeeding. Most people do (including me ). If they are unsightly, or you can see lots in the daytime wait till half an hour after the lights go out and scrape them off the walls. I just drop them into a bucket of boiling water. I normally do this once a year towards the end of summer as they reproduce like crazy when the water is warmer. Personally I would not get assassins.

Are you lights LED or fluorescent? If fluorescent the tubes should be replaced annually as they change colour over time. If LED and one strip is gone it may be worth replacing as the colour balance does eventually change as individual chips start to fail. The most obvious symptom is uncontrollable algae or generally unhealthy plants.

The tank in my signature is low light, its actually quite dark in there. I don't add CO2 and only rarely fertiliser. I do buy cheap plants, if they thrive in my tanks they stay - if not they go in the bin (but then I am known to be lazy )

Click to expand...

Hi again, do you have any idea where to get a suitable light for a Fluval Roma 200L? I'm stuck on where to find one that isn't £200+

The first photo is a tank with the lid, lights and in-built filter removed because one of the 2 fluorescent tubes no longer worked and I couldn't find a replacement. It's not a Fluval Roma, but the design is similar.
The 2nd photo is the same tank with 2 pieces of glass as cover, and a low cost LED light.

TNG said:

The first photo is a tank with the lid, lights and in-built filter removed because one of the 2 fluorescent tubes no longer worked and I couldn't find a replacement. It's not a Fluval Roma, but the design is similar.
The 2nd photo is the same tank with 2 pieces of glass as cover, and a low cost LED light.

Click to expand...

That looks amazing! Where did you get the light and glass? I have no clue where to start with glass...

ella777 said:

Hi again, do you have any idea where to get a suitable light for a Fluval Roma 200L? I'm stuck on where to find one that isn't £200+

Click to expand...

Have a look on Amazon - plenty of options. A lot of them are not fully waterproof and you will need a glass cover like @TNG suggests. I have a Nicrew branded one on one of my tanks that works really well (https://www.amazon.co.uk/NICREW-Aquarium-Spectrum-Freshwater-Extendable/dp/B08CXL9GBW). On another tank where I wanted it inside the lid I used a Fluval Aquasky - but they do cost more.

seangee said:

Have a look on Amazon - plenty of options. A lot of them are not fully waterproof and you will need a glass cover like @TNG suggests. I have a Nicrew branded one on one of my tanks that works really well (https://www.amazon.co.uk/NICREW-Aquarium-Spectrum-Freshwater-Extendable/dp/B08CXL9GBW). On another tank where I wanted it inside the lid I used a Fluval Aquasky - but they do cost more.

Click to expand...

I think I should buy a whole new lid & light for the tank. I'm not sure where I'd buy that from? I've looked on the fluval website and they don't have a replacement lid.
Theres a few that say "universal" so I assume they would fit any 100cm tanks?
My current working light is bowing, it's been like that since I got it in 2022 but I'm not sure how safe it is

If I was to do the glass/clear lid, where would I buy it from? I’d need a flap for feeding so it couldn’t just be a sheet of glass, but I can’t find any specifically made glass tank lids anywhere.

ella777 said:

If I was to do the glass/clear lid, where would I buy it from? I’d need a flap for feeding so it couldn’t just be a sheet of glass, but I can’t find any specifically made glass tank lids anywhere.

Click to expand...

Aqueon sells hinged glass tank tops for several sizes of tank length.