Plant filtration and Nitrates

[hart24601]

In 9.5 months if this peace lily was not limited by something, it would have been huge, as in my previous picture.....Mine grow on average 1.5 leaf weekly. 9.5 months is roughly 41 weeks, that's 61 new leaves....Peace lilies also multiply from the crown so one ends up with several peace lilies in the one pot....When they grow huge, they start flowering. They may need a bit of time to adapt to water conditions first when initially planted....I think your water lettuce may have scavenged all the ferts and the lily couldn't outcompete it as it looks like a small plant. Try it in a tank that has no lettuce...

I really didn't mean to imply peace lily wasn't suitable for this purpose or doesn't work at all, just showing some side by side pictures. I would guess that you are 100% correct that clearly they are being limited and I have do doubt they can grow much faster.

The plants in your pictures are amazing and look fantastic, clearly they are huge and you enjoy them and at that size they are consuming a great deal of nutrients.

However from my perspective I was looking at plants solely for nutrient consumption and the fact my specimen didn't grow quickly presumably to other plants out competing it would indicate to me that there are better options when it comes to a refugium style plant. Once again they look amazing in your system, but I don't have that sort of space to give them which is another reason I like WL because you can grow them in a very high limited space like under a tank in a refugium sump and just grab handfuls to export very quickly.

 

[Coryloach]

Yes, they are only suitable for larger tanks...I have no success with floaters because I use high filtration and high surface agitation..Plus as I said, my big emersed plants(once big enough) outcompete all type of floaters for nutrients unless I dose regularly...That same tank in the pictures above was started with tons of salvinia...all died a slow nitrogen deficient death in a few months when the large emersed plants took off....

 

[hart24601]

Good point! I'd love to discuss denitrification with you in depth sometime. I just finished my microbiology course as I am preparing for a thesis on probiotics. I suppose the methods of the study are what will determine the culprit. If they took sand from a natural environment, or possibly the water, then it is likely that these bacteria were present. They are actually facultative anaerobes, which will only denitrify when oxygen is not present. However, they can persist and survive even in an oxygenated environment. We clean our denitrifiers by bubbling air through them and denitrification resumes as soon as the chamber becomes anoxic again (less than an hour). Even when we bleach them we see denitrification the next day (haven't tested earlier than that). So if they used clean sand and water that are relatively absent of DN bacteria, then it's probably the plants. If they used seeded sand/water, then denitrification could have occurred. Does the article mention this in their methods?

I appreciate your input on this. I'm learning!

What are your denitrifiers? How large are they and what are you running through them? How much nitrogen do they remove when starting back up and over time? Any supplemental carbon and other macronutrients? I don't suppose you have any way to measure released gasses from them?

Before I left most of my time was spent with bacterial population dynamics. Taking 16s DNA and using next gen sequencing to look at populations pre/post some change to see how these communities differ because, as you know, bacterial populations are diverse and many interdependent so if you notice a particular phenotype change it can be a huge number of different pathways and organisms at play with the same result. PLus you can see population dynamics of unculturable bacteria with this method too.

Then for the next stage I looked at RNAseq to overlay with population changes so see what is really "happening" from a molecular side. Of course most of this was a year long plus type of projects. This work is expensive and requires a lot of bioinformatics which led me to my new career in analytic management.

I rambled a bit there. sorry all!

 

[Pomatomus]

You seem like a very informed guy but then you should know that you can't test accurately for nitrates even in lab conditions......The 160ppm you tested could have been far away from the real truth and what your mate was saying was probably true..

Very true, those API kits aren't too precise. The scale jumps from 160ppm to 200ppm, but they both look dark red. However, 0 nitrate reads yellow. I can't be certain that he had 160ppm, but I can be certain that my test was working well enough to indicate high nitrate. Far from 0.

What are your denitrifiers? How large are they and what are you running through them? How much nitrogen do they remove when starting back up and over time? Any supplemental carbon and other macronutrients? I don't suppose you have any way to measure released gasses from them?

I probably shouldn't go into every detail, but they are large cylinders about 8' tall and 4' wide. Water moves through them at about 30-40 L/min. After air exposure and mechanical agitation they reach typical efficacy within an hour or two. We supplement with molasses, and the flow rate is set based on the nitrate levels. Nothing else is added, just carbon and system water. Honestly there are a lot of things I would change about them, some of which are patent-worthy so I will keep them to myself

I am interested in denitrification with sulfur bacteria, but I have no experience with it. I think that's what SeaWorld uses if I recall correctly.

 

[Coryloach]

Very true, those API kits aren't too precise. The scale jumps from 160ppm to 200ppm, but they both look dark red. However, 0 nitrate reads yellow. I can't be certain that he had 160ppm, but I can be certain that my test was working well enough to indicate high nitrate. Far from 0.

This is what I am trying to say....When you test for nitrates, the colour does not indicate the amount of nitrates accurately, meaning that your colleague might have had anything between 5ppm to 200ppm...one will never know.....Testing for nitrate is completely useless...

Get a glass of tank water on which you've tested low nitrates such as 0-5ppm nitrates..Now add some magnesium sulfate or salt to it(none containts nitrates)....now test for nitrates again...You'll see a totally different nitrate reading without adding any nitrates..

The benefit of plants is that they alter the processes in the tank, using up fixed nitrogen before its been oxidised by bacteria and other processes...It is the chemical reactions in the tank that do the damage to fish as they alter the chemical composition of water....The end product nitrates is just a marker of organic pollution...if we were able to accurately test for nitrates...and we aren't....A TDS meter is a way better way of measuring organic pollution from water change to water change...Providing one doesn't dose any salts, in deteriorating water the TDS measure rises...Months of insufficient tank maintenance will result in near doubling the TDS reading from the source of water for water changes...You nitrate test may still be showing 5-10ppm when its possibly a 100ppm or vice versa...

The best way to control and test for the levels of nitrogen is by growing plants...such as floaters and emersed plants...A tank low on nitrogen will have nitrogen deficient plants pretty fast because nitrogen is required in higher amounts by plants than any other nutrient... You don't need denitrification in a planted tank....

Its interesting that plant sceptics are always those that have barely kept plants for any amount of time...

 

[Pomatomus]

This is what I am trying to say....When you test for nitrates, the colour does not indicate the amount of nitrates accurately, meaning that your colleague might have had anything between 5ppm to 200ppm...one will never know.....Testing for nitrate is completely useless...

Its interesting that plant sceptics are always those that have barely kept plants for any amount of time...

I think we're going to have to disagree about nitrate tests. This is the first time I've ever heard someone claim they are useless. I use colorimetric tests as well as electronic meters. The claim that a color near the top of the spectrum (in a tank with no added chemicals) could mean 0 is just beyond me. So much testing goes into these products before they are released to the public, and false advertising is a crime. Sure, in any test there are chemicals that can cause a false positive/negative, but when they aren't added directly the effects are most often negligible. It should also be noted that when you add salt you are skewing the color slightly, but color cards are provided for both fresh and salt water testing. They are different but very similar. Do you feel this way about other tests or just nitrate? False positives/negatives are possible in nearly all tests if you add the right chemicals.

And idk if you were referring to me with the last comment, but I have kept densely-planted tanks for most of my life. I have 7 of my own now and have maintained them for clients since 2010. I have probably cared for and monitored about 75 in total. Most of them for multiple years.

 

[Coryloach]

Do you feel this way about other tests or just nitrate?

Just nitrate. Its not about feeling that way. I know they are not accurate by a huge margin. Nitrates are not possible to measure in home conditions and almost impossible in a lab.

As for plants...also some research is needed if one is doubtful...There are numerous scientific papers on the nitrogen removal abilities of plants and a range of other toxins...They are used in waste water treatments, etc...There should be no argument about the huge benefit of plants in aquatic systems..

.If you want to test your water for nitrogen....see how well floating plants grow in yours.....It's an easy test to do......If they grow fast and lush without the need of additional ferts, the system has plenty of nitrogen at any given time....

 

[Coryloach]

And idk if you were referring to me with the last comment, but I have kept densely-planted tanks for most of my life.

No, I was referring to the ones that question the ability of plants to remove nitrogen....Its surprising though that someone who has kept densely planted tanks for years maintains an opinion that plants do not remove much nitrogen just because a nitrate test said so....

 

[Coryloach]

And idk if you were referring to me with the last comment, but I have kept densely-planted tanks for most of my life. I have 7 of my own now and have maintained them for clients since 2010. I have probably cared for and monitored about 75 in total. Most of them for multiple years.

Just curious...have you ever needed to add nitrorgen in any form to those planted tanks besides what's produced by fish? And are your plants healthy or just surviving..? Unhealthy plants won't do much good. Plants are like fish and need to be maintained to do their thing, even if that means adding nitrates...

 

[Pomatomus]

No, I was referring to the ones that question the ability of plants to remove nitrogen....Its surprising though that someone who has kept densely planted tanks for years maintains an opinion that plants do not remove much nitrogen just because a nitrate test said so....

Like I said in my first post, I learned this from a dissertation that performed a mass balance. I must concede that it only tested 3 aquatic macrophytes, but they found that in an intensive system the primary nitrate loss was from denitrifying bacteria. It's not that plants don't remove much nitrogen, they just weren't the most effective in that case. What bothers me is that they are often touted as a cure-all for reducing nitrogenous waste. My coworker with the tank I tested was asserting that he only needed water changes every few months because his plants keep the nitrates low. My test disproved this and he now does weekly water changes. My overall point was that I wish denitrification received more attention in the aquarium hobby, as it is a very effective method of removing nitrates. So much so that it alone can keep nitrates to a minimum, as is evident from saltwater tanks.

Just curious...have you ever needed to add nitrorgen in any form to those planted tanks besides what's produced by fish? And are your plants healthy or just surviving..? Unhealthy plants won't do much good. Plants are like fish and need to be maintained to do their thing, even if that means adding nitrates...

No I personally haven't had to add any nitrogen, just minerals. My plants are healthy - I can provide pics if you want. My personal tanks make about $200 per year in store credit from plant sales.