Weak plants and algae

[insalacosm]

Hello, I’ve been struggling to maintain healthy plants since setting up my tank a few years ago. Earlier this year I added CO2 in hopes that it would solve my problems of weakening plants and bearded algae growth, but I don’t see much of any improvement. I have the lights on for 8 hours per day and do 35% water changes every two weeks. I add liquid fertilizer every week and have placed fertilizer rods in the substrate at the roots. Basic water tests all look good.

What I see happening over and over with all plants is the leaves become weak and thin, or bearded algae begins to grow around the edges. The red colored plants fairer the worst and didn’t survive more than a month. I’ve tried different variety and none are doing well. I live in the Netherlands and the water here is very hard but doesn’t contain any chlorine.

Any ideas on how I can improve the strength of my plants and decrease the bearded algae growth?
Thank you,
Steve

 

[Aiken Drum]

It looks like carbon or nitrogen deficiency to me.

What are your nitrate levels like?

Aquarium plants are going to get carbon from either disolved CO2 or carbonate hardness. You have tried injected CO2. You say your water is hard, are you referring to general hardness (GH) or carbonate hardness (KH) or both. That's a little odd, because I was under the impression that water in The Netherlands was soft.

How long have you left the plants in the aquarium after you started to see plant melt?

Commercially grown plants are cultivated “emersed” rather than “submerged”. This way the plants can easily get their carbon requirement from atmospheric CO2. They can be grown quicker which makes the operation much more commercially viable. You take that plant, put it in your aquarium, cut off its source of CO2 and the plant goes into survival mode. It starts to use up its stored carbon and the leafs melt. You may lose all your original growth to melt but new leafs will have a structure more suited to its new environment and get its carbon from the water. Plant melt is a normal stage in aquarium plant growth. To judge the health of a plant look for new growth rather than what might be happening to the original growth, and judge it over extended periods of time.

 

[insalacosm]

Hi Aiken,
Thank you very much for the reply. Here’s a picture of my latest test. It shows nitrate levels being anroind 10 and KH around 4.5. I assume these are okay as they are in the low end of the spectrum but not sure. My test doesn’t include a GH measurement. When I say the water is hard, what I mean is there’s a lot of calcium in the water which leaves mineral traces when it dries.

The taller plants with stems typically lose their leaves in about one month and then the stems rot away as do the roots so we remove the entire plant. The plants with larger leaves coming out of the bottom have survived for one year or more and those with thicker green leaves seem to be doing the best, although they develop bearded algae around the edges. Those plants with a thinner, lighter color leaf and pointed tips become very thin and almost transparent, especially the new growth. I’ve also noticed that the new growth on the taller stemmed plant is lighter in color and the leaves are not as wide.

We increased the depth of the substrate, so maybe that will help the root development, but everything seems to be growing very slow and then quickly taken over by algae.

Thanks,
Steve

 

[Aiken Drum]

A few points.

Test strips are notoriously unreliable. You really can't trust what they tell you. They don't test for ammonia which is the most important test as that's the first parameter to go off if something is wrong, so you have to buy separate ammonia tests which makes them both uneconomic and unreliable.

However let's take your tests at face value.

Nitrate + nitrite. The presence of nitrate and no nitrite is an indicator your cycle is established, which is good, but nothing to do with your plant issues. You are correct that low nitrate is good for fish, but its bad for plants. I mentioned nitrogen in my above post, and plants typically get their nitrogen from nitrate. 10ppm is at the low end of what's a good parameter for plant health. Somewhere in the range of 10 to 20ppm nitrate is going to be a good level for both your plants and fish. If your test was after a water change that's probably going to be OK as the nitrate levels will increase before your next water change and keep you in the 10 to 20ppm range. If your test was before your water change it could do with being a bit higher, as your water change will lower the nitrate level below that 10ppm, and then gradually increase back up to 10ppm before your next water change again lowers it.

You do have a general hardness test on there. Your GH is below 6 degrees, which is considered soft. So your water doesn't contain much calcium in it. This could either be down to my point about the accuracy of test strips, or you are mistaken about your water being hard.

I agree your KH is somewhere in the 3 to 6 range, which again would be considered low. Low nutrient demand plants often get their carbon needs from KH, so plants usually do better in harder water.

So your water if we accept the test results as accurate isn't ideal for healthy plant growth.

You have a few options.

Nitrate. You could cut back on water changes to see if that gets the nitrate a little higher. But you arent really changing much water as it is, so I wouldn't reduce further. Add more fish maybe. Or, most aquarium fertiliser products don't have a lot of nitrogen (nitrate) in them as they are perceived as being responsible for algae. What fertiliser are you using? Some fertilisers do have nitrogen in there though.

Water hardness. I would get an accurate test and not rely on the strips as they contradict what your own understanding of what your water hardness is. If we did take your KH as accurate, while it's soft it's not so soft that it would cause any issues. A question though. Does your tap water go through a water softener?

Algae is a result in inbalance of nutrients, carbon and light. From what you have said carbon and nutrients are both low, so how about your light? Do you know the specs of your light? Does your aquarium get any natural daylight? 6 to 8 hours of aquarium lighting is usually sufficient for healthy plant growth while not driving too much algae growth. Contrary to common sense your light might be too much. If you have a strong light, or if its turned on for too long what will happen is that the light will drive plant growth, but as there are insufficient nutrients and carbon that plant growth can't be healthy. Too much light will also cause algae growth. Both of which you are seeing.

And a couple of final points.

Not all plants will do well in all aquariums. Keep the ones that do well and get more of those, and remove the ones that don't do well. I've tried numerous plants in various tanks to find the ones that do well in my particular set up.

Keeping plants is about trial and error. Try something, only one thing, and observe how it affects your plants over a few months. Any change, positive or negative, can then be put down to that one change. And then adjust something again and see what effect that has, again over a few months. So you might try reducing the light intensity, or duration. Or you might try a better plant fertiliser. If you change too many things at once you don't which change caused whatever effect you observe.

 

[insalacosm]

Hi Aiken, thank you very much for the analysis and recommendations! The test was done just before a water change so the nitrate levels were probably at a higher point than the prior two weeks. I’ll see about having a more detailed test done at a garden center that offers that service.

The plant fertilizer I use is Easy Life ProFito. I looked it up and they actually say that their fertilizer doesn’t contain nitrate or phosphorus since these are normally occurring when there’s enough fish, but if there’s not enough fish, then more nitrate is needed, as you suggested.

I also have an outdoor pond and have a additive Columbo to increase the GH. If the professional water test shows a low hardness, do you think it would be OK to add some of this even though it’s made for outdoor ponds?

Regarding the light, I have the light on for 8 hrs a day. During the summer when there’s a lot of ambient light, there’s definitely more of an algae issues so you may be onto something with your recommendation to lower the amount of light. The lamp is the standard that was provided with the kit, a Juwel NovoLux LED White 60 cm.

The plant seemed to be doing a little bit better than they have in the past, maybe this is due to slight increase in the fertilization and the thicker substrate. Some of the older plants that have new growth look good although the new growth has a lot of algae around the perimeter of the leaves.

Thanks,
Steve

 

[Aiken Drum]

There are a few fertilisers that contain a decent amount of nitrogen. I see from your bio you are from the Netherlands, and I'm not sure what's available there. In the US, NA Thrive comes highly recommended. Here in the UK we have TNC Complete. I've found a product called Easy Life GreenScape that says it has nitrate and phosphate, so if you can get ProFito you should be able to get GreenScape.

I'm not suggesting you need to increase your GH, just stating that your test indicates its considered soft. Your KH is low, but as said its not so as to appear to be an issue. If you keep up with water changes to replenish KH that should be sufficient. But it's something you could try as a "trial and error" thing. The GH product will increase GH only, not KH. It's not a product I'm familiar with, so while I have no reason to think it isn't safe for aquariums, I would with the manufacturer if you wanted to add it into your aquarium. If it's a pond product that probably means concentrated for easier dosage in larger volumes of water. That might make it difficult to accurately dose in smaller volume aquariums.

Remember that mucking about with water chemistry can rapidly change water parameters which can cause shock to fishes systems and sometimes kill them. So don't make big changes in one go.

Personally I'd look at the different fertiliser to start with. Try and get the nitrate consistently in the 10 to 20ppm range for a month or two and see if that improves things.