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Have a fairly new 29 gallon freshwater tank at work. Using 72 watts total lighting. 2 ea. 6700 k bulbs and 2 ea. colormax bulbs. Substrate is CaribSea Floramax. Run the lighting 7 hrs per day. The plants are beginning to develop brown spots on the leaves. My Cardinal Plants (Lobelia cardinalis) are the hardest hit. Is this a CO2 problem or does the substrate lack the micronutrients to fully sustain the plants?

Leaf Annual plant Plant stem Herb Herbaceous plant
 

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I'm pretty sure it's a nutrient deficiency. Not enough CO2 can cause algae to take over, but it won't brown your leaves.
 

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Cardinal plants are not true aquatic plants. If planted submerged, you have to take them out once or twice a year for a few months at a time to grow emersed then replant them in the aquarium.

Cardinal plants also have the ability to grow bright red leaves along with other various shades. I do not know personally of this plant as I have never tried to grow it. But those spots could be indicative of a lack of iron. Red plants have a tendency to be iron hogs.
 

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Cardinal plants are not true aquatic plants. If planted submerged, you have to take them out once or twice a year for a few months at a time to grow emersed then replant them in the aquarium.
where are you getting your information about cardinal plants not being a true aquatic plant??
 

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You said other plants are getting spots as well? Do you have any pics of the spots on the other plants?

Can you rub off the spots?

It does not look like a deficiency. The symptoms don't match any of the common deficiencies. Its not CO2 or iron related.
 

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are you law enforcement?
no, why do you ask? my original question about citing your post was simply because I wanted to read more on the topic since I keep lobelia cardinalis, wasn't accusing you of making something up, sorry if I came off rash.
 

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no, why do you ask? my original question about citing your post was simply because I wanted to read more on the topic since I keep lobelia cardinalis, wasn't accusing you of making something up, sorry if I came off rash.
Ha, no no. You just said 10-4. Common law enforcement term. Was just curious.
 

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You said other plants are getting spots as well? Do you have any pics of the spots on the other plants?

Can you rub off the spots?

It does not look like a deficiency. The symptoms don't match any of the common deficiencies. Its not CO2 or iron related.
How accurate do you believe that deficiency finder is? I just looked at the website and I didn't find a whole lot of information on it. Without sources, I cannot say whether or not the information is credible. For example, the section on CO2 deficiency has an example with anubias. Anubias are one of the easiest plants ever to grow in almost any conditions. And they absolutely do not need CO2. Also, I am currently growing Rotala Rotund very well without CO2 at the moment. I am not saying the information is wrong, I am just not sure how easy it is to list types of deficiencies and give one example.
 

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VThompson - after seeing the wisteria in the second photo it looks like you have an iron deficiency going on. This occurs as pale new growth with normal sized leaves. Eventually the leaves will develop clear patches and begin to die. The old growth stays green and healthy.

The brown spots you have are unrelated to the iron deficiency whatever they are (probably diatoms or algae as monster_fish mentioned).

How accurate do you believe that deficiency finder is? I just looked at the website and I didn't find a whole lot of information on it. Without sources, I cannot say whether or not the information is credible.
A fair question. When I made the deficiency finder I did quite a bit of research reading through primary literature looking for the visual symptoms of each deficiency. I then confirmed nearly all the entries that are on the website either personally or by helping people through the problem and replacing the missing nutrient. When I did it personally I used a number of different methods to confirm the deficiency. First I used a test kit if I had it available, if I did not I had my water source analyzed by a professional, then I replaced just the missing nutrient and watched for recovery which happened within a few days. With other people's photos we went through a similar process - match the symptoms with known literature symptoms, test the water if possible, then add back the missing nutrient and see if the plant recovered. Perhaps I will start adding links to the threads where we worked out what the deficiency was so people can refer to it for further reading?

For example, the section on CO2 deficiency has an example with anubias. Anubias are one of the easiest plants ever to grow in almost any conditions. And they absolutely do not need CO2.
The thing with CO2 deficiency is there is very little literature on actual CO2 deficiency symptoms. The few papers I've been able to find and read clearly state that there are no physical symptoms for plants placed in a CO2 free environment. In other words, the plant will not show damaged or curled leaves. It just stops growing - frozen in time.

While the plant itself does not degrade according to the literature there are a few visual cues that signal CO2 is missing. Some plants are able to use the carbonates and bicarbonates in the water column (the KH) and break it down into CO2 which they can use to fuel their growth. This causes white scaling to build up on the leaves. While I did not test the build up on the Hydrilla and Anubias plants to be 100% sure it was calcium, I see few other possibilities given that both of these species are known to be capable of carrying out this process, the tanks were not CO2 injected, were very warm (less dissolved gas), were densely planted and had no water flow.

Also, I am currently growing Rotala Rotund very well without CO2 at the moment.
The Rotala picture was taken in the same tank as the Anubias with white biogenic decalcification (carbonates --> CO2 process) and showed no signs of damaged growth, but also virtually didn't grow at all, or did so extremely slowly over the course of several months. The circumstances that lead to a true CO2 deficient tank are fairly uncommon and from what I have seen online over the last several years tells me that 99% of the time the plant problem is not CO2 related at all. In fact, adding CO2 can actually make other deficiencies more common. CO2 is basically a growth accelerator. If you add unlimited amounts of CO2 to a tank plants will grow up to 5x faster than non-CO2 injected tanks, this means you need to be keeping up with the other nutrients or one of them is likely to run out leading to a nutrient deficiency.

Since the idea that a lack of CO2 causes all kinds of plant growth problems is so pervasive on the forums I'm currently putting together a small test chamber which will allow me to remove nearly 100% of the CO2 inside it but not the other gasses in the air so I can see what a real acute deficiency looks like. It will probably take me a few more weeks to get everything setup and running, but I'll post high definition photos of the process day by day and run a control tank next to it with the same light/heater/power head/etc except I'll add CO2 and see how the two compare. I might even run a third control tank with no added CO2 to show the difference.

I am not saying the information is wrong, I am just not sure how easy it is to list types of deficiencies and give one example.
It is always a good idea to be curious and check sources whenever you can so I admire you for asking. People usually do not check primary sources and are often mislead or help perpetuate bad advice (like CO2 deficiencies are common & show up as all sorts of damaged growth) out of ignorance.

Nutrient deficiencies also show up with fairly consistent symptoms in almost all plants. This is because nutrients are used in virtually the same way and for the same purpose in most plants, and so when the nutrient is missing plants will degenerate in predictable ways across species. Of course there are always species-specific differences but these are usually minor variations. For example, iron deficiency in almost all plants occurs in the newest leaves, though some plants will develop it in middle aged leaves first. Iron deficiency usually shows up as completely white veins and leaf tissue, but in some species like Hygro. corymbosa it shows up as only white tissue between green veins in the new growth. In almost all plants once iron is replaced the plant will continue growing healthy green leaves but the white leaves that were formed will remain white, though in Helanthium bolivianum 'latifolius' white leaves will regain almost all of their green color once iron is added.

While I cannot say that every single photograph I have gathered in the database is 100% correct (I simply lack the necessary equipment to do tissue analysis to prove it directly and definitively), I have done my best to use the tools and equipment available to me personally (literature database symptoms, water analysis, photographic proof, single nutrient addition) and help walk others through the process of confirming the cause and solution to a given problem.

Ideally I'd like to do during, then after shots for each plant and each deficiency something like I did for R. macrandra in nitrogen deficiency and in potassium deficiency but it is time consuming.

Nitrogen - see image 2
http://deficiencyfinder.com/?page_id=620

Potassium - see image 2
http://deficiencyfinder.com/?page_id=649

If you'd like to read more about any particular deficiency in general I can send you the title or place I found a good description of it, or provide you with the thread for a particular deficiency entry if you'd like to read through it.
 

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Zapins,

Sounds awesome.

While extremely time consuming and tedious, you may be on to something in terms of putting together a database in which you are able to show multiple types of deficiencies in a large variety of plant species. For example, you show Rotala Macranda and it's deficiencies with potassium. What if you were able to include other deficiencies such as iron, light etc. and continue on with multiple plant species.
 
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