Trouble keeping plants alive in low light

[Irksome]

I’m trying to keep my tank looking beautiful but I keep running into issues. Plants keep dying, even some of the apparently easiest to keep. Im hoping for help from someone with “low tech” experience. I cannot easily add light or c02 other than changing the bulb. I’m running an Arcadia 18inch t8 as fits my hood, the tank is 10 gallon. The temperature is kept at 25centigrade or 77f. The ph is 7.8-8. the water is hard. The substrate is gravel. I dose liquid ferts once a week and I’ve used clay balls and jelly capsule style root tabs(stopping as they cause nitrate spikes). All the plants were chosen from lists of “low light plants”
The plants that are thriving and visibly growing are:
Anubias nana and java fern - both grow a new leaf every week or two.
Amazon frogbit - seems happy enough unless it gets fish food on it.

Plants that have failed to thrive are:
java moss-dead, all dead from multiple sources on different places around the tank, this is my biggest disappointment.
bacopa- all died
Water wisteria- all died
Anacharis- half died, poor colour no grown
Ludwigia - slow growth, poor colour
Aponogeneten crispus- too leggy
Water sprite- had algae problems and died.
Others that are new to the tank and have not immediately died are amazon sword, vallis and cryrtocoryn walkerii.
If anyone can help, have I missed any plants that may be suitable?
Is there a better bulb that may be suitable? I have a spare that is a generic “daylight 6500k”.
My next plan if conditions cannot be tweaked effectively For a variety of plants is to just get lots of Anubias varieties. I’m hoping for a rich jungly look.

 

[Essjay]

I have low light, slow growing plants attached to wood and they don't have problems even with just about the entire surface covered with water sprite.

Java fern (I have the windelov variety)
several species of anubias
Bolbitis heudeloti
two species of bucephalandra.
bits of java moss attached randomly to wood (where it floated to, I didn't attach it)
And water sprite used as a floating plant, which now covers 95% of the water surface.

The only fertiliser I use is Seachem Flourish (comprehensive supplement) used at half the recommended dose.


As you can see, the plants that are thriving in your tank also thrive in mine. I could never keep plants alive until I used only plants which grow attached to decor. If you are failing with plants grown in the substrate, maybe you could try bolbitis and bucephalandra which grow well in my tank.



Oh, nearly forgot. I used to have hornwort in the tank. I got rid of it because it was taking over and threatening to strangle the other plants. I found it grew well with the stems twisted around wood with lots of branches rather than planted in the substrate. You could try this to create the effect of stem plants.

 

[Irksome]

Thankyou for your reply! Those are some great suggestions. I will look for good suppliers of some of these plants.

 

[utahfish]

Ive done low tech as well. Ive found bacopa needs more light to thrive, and that anacharis does as well. Anacharis is a heavy feeder and when light and nutrients are insufficient they get spindly and thin and brown.
Tom Barr from the Barr report has said the 2 most nutrients plants are insufficient in are Potassium and Iron. Potassium is a Macro nutrient so make sure whatever fert you are using has potassium in it. Iron is a micro nutrient and is tougher to dose because sometimes its not chelated properly or in a form that plants can utilize and sometimes can block the absorption of other nutrients.
Sone plants also do better in soft acidic water and youve stated you have hard water. There is a relation between acidic water and carbon availability hard water usually is associated with a higher ph which decreases available carbon. Some plants need more carbon than others. Id stick with java fern and anubius both plants that do well in low light and hard water as they need the calcium and id stick with crypts. There are alot of different crypts from bronze green even red lots of different shapes and sizes all crypts are heavy root feeders so make sure they have root tabs by their roots and they also will benefit from the calcium in the hard water. Swords are heavy root feeders as well and will consume alot of nitrates and nutrients, they need root tabs and will greatly benefit from added potassium and iron and while they do better in soft acidic water they can do hard water. I dry dose with k2so4 for my potassium which is potassium sulfate and while i dont directly dose iron, iron gluconate is effective and is usually in some comprehensive liquid and root ferts. Id stick to those four, java fern, anubius, crypts and swords and avoid stem plants and any red plants. Also Vals might require more light as well and are heavy feeders as well so id avoid them as well as small carpeting plants that require stronger light than you have. Good luck!

 

[Byron]

Aquatic plants require sufficient light to drive photosynthesis, and then sufficient nutrients to balance the light. Both depend upon the type of plants. Slow growing plants need less intense light and less nutrition than fast growing species. This applies to terrestrial plants as well, as anyone with a garden can tell you.

Spectrum is also critical when it comes to the light. Aquatic plants require red and blue light for photosynthesis, and red is the more important of the two. Adding green to the mix does improve plant growth. The "daylight" tubes with 6500K are ideal for this. But, the manufacture of the tube can also affect this. I have had 6500K tubes that were not adequate, and some that are incredible.

My first suggestion would be to replace the tube. The "generic" 6500K you have might work--what is the manufacturer? On my single tube tanks with T8 fluorescent I only use Life-Glo; more expensive, but they are in some cases 1/3 to almost twice more light because of how they are manufactured (the phosphors). The ZooMed Ultra Sun is a close second. Both of these are 6500K. To illustrate the difference with some less expensive tubes, when I used a GE 6500K over the 29g the plants that had been doing well under Life-Glo began to die off within just a very few weeks. I replaced the GE with a new Life-Glo and the plants that had not fully died began to respond. T8 tubes need replacing about every 12 months regardless; after this time they lose too much intensity.

Nutrients is easy to provide. Use a comprehensive supplement. Substrate tabs benefit substrate-rooted plants like swords. Liquid fertilizer benefits all plants including floaters and those not rooted in the substrate. Seachem's Flourish Comprehensive Supplement for the Planted Aquarium and Brightwell Aquatics FlorinMulti both provide all necessary nutrients and just as importantly in the proportion to each other than plants need. This avoids overdosing this or that nutrient which can not only cause algae but lead to plant and fish issues.

The other issue is to have plants with similar requirements respecting light and nutrients. Some slow growers with fast growers are possible, but you cannot get too far apart. This too is like gardening; bright light plants will not grow in shade. I personally would not grow stem plants in a 10g tank as they are so fast growing you will be continually pruning them out.

 

[PheonixKingZ]

Your Anacharis should be taking off by now. Wait, do you not even have a light?

 

[Irksome]

Ive done low tech as well. Ive found bacopa needs more light to thrive, and that anacharis does as well. Anacharis is a heavy feeder and when light and nutrients are insufficient they get spindly and thin and brown.
Tom Barr from the Barr report has said the 2 most nutrients plants are insufficient in are Potassium and Iron. Potassium is a Macro nutrient so make sure whatever fert you are using has potassium in it. Iron is a micro nutrient and is tougher to dose because sometimes its not chelated properly or in a form that plants can utilize and sometimes can block the absorption of other nutrients.
Sone plants also do better in soft acidic water and youve stated you have hard water. There is a relation between acidic water and carbon availability hard water usually is associated with a higher ph which decreases available carbon. Some plants need more carbon than others. Id stick with java fern and anubius both plants that do well in low light and hard water as they need the calcium and id stick with crypts. There are alot of different crypts from bronze green even red lots of different shapes and sizes all crypts are heavy root feeders so make sure they have root tabs by their roots and they also will benefit from the calcium in the hard water. Swords are heavy root feeders as well and will consume alot of nitrates and nutrients, they need root tabs and will greatly benefit from added potassium and iron and while they do better in soft acidic water they can do hard water. I dry dose with k2so4 for my potassium which is potassium sulfate and while i dont directly dose iron, iron gluconate is effective and is usually in some comprehensive liquid and root ferts. Id stick to those four, java fern, anubius, crypts and swords and avoid stem plants and any red plants. Also Vals might require more light as well and are heavy feeders as well so id avoid them as well as small carpeting plants that require stronger light than you have. Good luck!

Thankyou for the reply. There is plenty here for me to look into. Being new to the hobby I think I got over excited by the variety of plants that many a website promised would thrive in my conditions.

 

[Irksome]

Aquatic plants require sufficient light to drive photosynthesis, and then sufficient nutrients to balance the light. Both depend upon the type of plants. Slow growing plants need less intense light and less nutrition than fast growing species. This applies to terrestrial plants as well, as anyone with a garden can tell you.

Spectrum is also critical when it comes to the light. Aquatic plants require red and blue light for photosynthesis, and red is the more important of the two. Adding green to the mix does improve plant growth. The "daylight" tubes with 6500K are ideal for this. But, the manufacture of the tube can also affect this. I have had 6500K tubes that were not adequate, and some that are incredible.

My first suggestion would be to replace the tube. The "generic" 6500K you have might work--what is the manufacturer? On my single tube tanks with T8 fluorescent I only use Life-Glo; more expensive, but they are in some cases 1/3 to almost twice more light because of how they are manufactured (the phosphors). The ZooMed Ultra Sun is a close second. Both of these are 6500K. To illustrate the difference with some less expensive tubes, when I used a GE 6500K over the 29g the plants that had been doing well under Life-Glo began to die off within just a very few weeks. I replaced the GE with a new Life-Glo and the plants that had not fully died began to respond. T8 tubes need replacing about every 12 months regardless; after this time they lose too much intensity.

Nutrients is easy to provide. Use a comprehensive supplement. Substrate tabs benefit substrate-rooted plants like swords. Liquid fertilizer benefits all plants including floaters and those not rooted in the substrate. Seachem's Flourish Comprehensive Supplement for the Planted Aquarium and Brightwell Aquatics FlorinMulti both provide all necessary nutrients and just as importantly in the proportion to each other than plants need. This avoids overdosing this or that nutrient which can not only cause algae but lead to plant and fish issues.

The other issue is to have plants with similar requirements respecting light and nutrients. Some slow growers with fast growers are possible, but you cannot get too far apart. This too is like gardening; bright light plants will not grow in shade. I personally would not grow stem plants in a 10g tank as they are so fast growing you will be continually pruning them out.

The generic bulb is a syvania, the Arcadia I have is 7500k but I can get glolife bulbs in my country so I will try that next I think and stick to less varied plants.

 

[Irksome]

Your Anacharis should be taking off by now. Wait, do you not even have a light?

I have a t8 18” florescent 7500k aquarium bulb, I think it might be rubbish. It also gets coated in lime scale... I’ve removed the dying anacharis and put it in a jar in the window. It already looks better

 

[Byron]

The generic bulb is a syvania, the Arcadia I have is 7500k but I can get glolife bulbs in my country so I will try that next I think and stick to less varied plants.

The 6500K you have (assuming it is not older than a few months of use) will be better than this 7500K. But being Sylvania I would think it will be weak like the GE I tried. I had very good plant response from Sylvania or Phillips 6500K tubes but only the 4-foot tubes that went over my larger tanks. The smaller tubes failed. So the Life-Glo is your best bet. In the meantime, change to the Sylvania, it might improve things.

 

[utahfish]

The generic bulb is a syvania, the Arcadia I have is 7500k but I can get glolife bulbs in my country so I will try that next I think and stick to less varied plants.

You dont need anything higher than 6500K anything higher has more blue light than red and is better for growing corals not plants.
Anything between 5000K and 6500K is considered " daylight" more importantly than color spectrum is lumens PAR and CRI. Lumens is the amount of " energy" the bulb provides to the plants, for LED the suggested range for lowlight plants is 20-30 lumens / liter of water. For flourescent its 2 to 3 watts/ gallon.
PAR measures the light ability to penetrate the water. Lights availability at the surface will be greater than at the bottom of the tank surface. Recommended PAR at delth of tank for low light plants is 30. CRI measures how much of individual colors a bulb has. Plants respond best to red and blue sone white and a little green. Bulbs with high amounts of reds and blues will have a higher CRI rating. 90+ is recommended.
Having said all that its alot, ive been trying to grow plants for about 15 years now and its alot of info for me that is always changing and improving so good luck finding what works for you.

 

[PheonixKingZ]

If it’s covered in lime, it’s about to go. (That’s not a symbol, but it means it’s been there a while.) Get a new bulb, that’s my advice.

 

[Irksome]

Covered in limescale in under 6 months, I’m probably not going to be getting a year of good use from each bulb.