Old Tank Syndrome, Nothing Helps, NO3 Test Makes No Sense!

jfcp · Dec 26, 2020

I have a heavily planted 20 g long (set-up details at bottom of post) that had excellent plant growth for a couple of months, then things (for the plants) slowly started to go downhill.

Without even trying, I used to grow more hornwort, lily pads, Chiliensis than I knew what to do with, now the hornwort is about all gone. First the floating hornwort slowly, over weeks, months, turned brown and disintegrated, regrowing somewhat in spurts, then dying back, but trending slowly down. Meanwhile, for a long time, many rooted plants - like Aponogeton, Java Fern, Pond Lily, Chiliensis, Java Moss, Mondo Grass, grew well or at least remained stable, then first the Aponogeton, then the Mondo grass began to die off. Now, a few weeks later, even the last 5 in the previous list are not looking as good, mainly turning brown or yellow, leaves losing color, then disintegrating, Java Fern getting black spots all over, seems to be deteriorating. Only a couple of species - like "Marimo moss" and duckweed appear to be unaffected.

I have been using SeaChem Flourish and Fritz trace elements all along, but even increased doses make less and less, if any difference now. Weekly water changes of 60% used to do some good, but now have less effect, if any.

My nitrogen cycle tests were giving 0 or near 0 ppm for ammonia, nitrite, and nitrate, so I tried more extreme measures, and immediately ran into weird difficulties: Making an additional diy nitrate fertilizer from KN03 crystals, and using the Rotala Butterfly Nutrient Calculator

One moment, please...

Per the Calculator results, I added 1.85 grams of KNO3 to my 20g long, aiming for 15 ppm KNO3, waited a couple of hours, retested for nitrate (the API Freshwater Master Test Kit 800) AND STILL GOT 0 ppm NO3!

I made a ridiculously strong sample of KNO3 solution to test, in order to assure that at least the test kit chemicals would change color, (the kit is NEW; chemicals all have date-codes showing they expire in 2025!) and that test "worked', at least to the extent of proving a color change was possible.

But it gets weirder:

After a day or so, I thought perhaps some of the plants looked just a bit greener, so on the assumption that Google search was not going to kill me, i.e. that 40 ppm NO3 was safe, I shot for 30 ppm by adding another 1.85 grams KNO3, waited, re-tested the water for NO3, using the same kit, AND STILL GOT 0 PPM NO3 !!

So question #1 would be : Anyone had trouble with the API Freshwater Master NO3 test or the Rotala calculator?

Suggestions for another NO3 test?

I'm guessing perhaps I could need iron supplementation, or CO2 injection to increase bio-available carbon, not nitrogen, but my Ph was 6.5 - 6.7 already, and that's too close to the lower limit.

The problem could also be the substrate; I have Eco-Complete, and have heard that this type of material loses its effectiveness after a while. Could I need to add laterite, clay shards or something ?

I should mention I have HARD water, ~ ph 7.6, Kh ~211 ppm as it goes into the tank, (dechlorinated w/ SeaChem Prime, oxygenated & stored for 7 days prior to use), and a large colony of many hundreds of Malaysian Trumpet snails in the substrate (mainly), and I know snails can lower ph a bit by extracting carbonate, but THAT much (7.6 - 6.7 or lower)? Probably not.....

I should mention all fish & invertebrates seem to be fine; no ich, no rot, except one or two fish do scratch a bit, as from a cilliate, but there are no visible signs of disease anywhere on them, & 3/4 of the fish do not scratch at all - only 1 loach of 3, 1 cory of 3, & the Back Ghost does get white scratches now and then, which disappear in a day or so, but which don't seem to correspond to where he scratches.

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Recent test results;

Temp; 79 F

Ammonia, Nitrite, Nitrate, all ~ 0 ppm (!?!)

ph 6.5 - 6.7

Kh ~17.9 ppm

Gh ~ 130 ppm

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SET-UP:

20 gallon-long w/ glass top

Eco-Complete substrate

20-50 g AquaClear HOB

2 sponge filters, in rear corners, each has a "40g" TETRA air-pump on it (PLENTY of aeration !).

48 W, full-spectrum LED light, 16/8 day/night cycle w/ dawn/dusk feature, w/ blue night light.

LOTS of live plants, as above.

100W heater, temp constant ~ 79F

1 piece Mopani wood (adds a bit of tannin)

Weekly water change ~60%, HARD water

------------------------------------------------------------

STOCK:

1) 5-6 inch Black Ghost Knife

3) Yoyo Loaches, 2-3 inches long

3) Corydoras

1) 2-3 inch Chinese Algae Eater

1) Pleco, ~3-4 inches

6) Neon Tetras (weird, I know. but no problems)

~15) Ghost Shrimp

2) Nerite Snails

Several hundred Malaysian Trumpet Snails.
-----------------------------------------------------

mark4785 · Dec 26, 2020

I’ve never experienced any issues with the API nitrate testing kit. Double check that it is not out of date and double check you are not using any filter media or substrate that is classed as an ammonia and nitrate remover as all these factors could affect accuracy.

It sounds like something in the tank water is interfering with the result.

As for plants that disintegrate, i’ve only had this happen where a large water change is done that changes the water chemistry sufficiently to kill the plant, i.e with crypt melt and Valis die back. It can also be caused by having inappropriate hardness or temperatures.

You may wish to also look at your KH reading as this is responsible for buffering the pH level of your tank. With a huge uptake of carbonates by the plants and snail waste oxidation, the KH could be becoming depleted which in turn could be making your pH crash. Plants wont like this if it is happening.

Colin_T · Dec 26, 2020

Aponogetons and other plants that have bulbs will usually do well for a few months and then slowly go downhill. This is caused by a lack of nutrients and the plants use the reserves in their bulbs to grow for a bit, then they run out of nutrients in the bulb and slowly die.

--------------------
As for adding potassium nitrate to the tank, nitrates are not found in the wild and whilst terrestrial plants might use it, aquatic plants have to convert nitrates into ammonia before they can use it. There is normally sufficient ammonia in the water from fish food and waste to provide plants with the nitrogen they need.

--------------------
There is usually sufficient carbon dioxide (CO2) in the water for aquatic plants. CO2 is produced continuously by filter bacteria and the fish, shrimp and snails in the tank. CO2 also gets into the tank from the air and is produced by plants when it is dark and they are resting.

If you want to add CO2 to an aquarium, it should be done carefully and preferably before fish are added, just in case it goes wrong and you kill all the fish by adding too much CO2.

When using CO2 in aquariums, you need to buffer the KH to prevent the CO2 dropping the pH.

--------------------
Without seeing pictures of the plants, I would say they are suffering from a lack of nutrients and or a lack of light. Duckweed and other floating plants can reduce the amount of light getting to plants lower in the water column.

Most aquarium plants do well with an iron (Fe) based aquarium plant fertiliser that also contains trace elements.

Aponogetons like a lot of nutrients and your substrate probably isn't providing enough now. As you mentioned, most plant substrates do eventually stop helping plants grow and either need to be replaced or other things added. I used red or orange clay, which I rolled into balls about 10mm diameter and put these in the gravel under the plants. And I added an iron based liquid plant fertiliser regularly. I used an Iron (Fe) test kit to monitor iron levels and keep them at 1mg/ltr (1ppm).
Each week I did a big (75-90%) water change to remove any unused fertiliser and this helped prevent poisoning the fish.

--------------------
Aponogetons and other heavy feeding aquatic plants can be grown in pots in the aquarium. This way you can provide them with more nutrients but trap/ confine the nutrients to the pot and not let them get into the water.

We use to grow plants in 1 or 2 litre plastic icecream containers. You put an inch of gravel in the bottom of the container, then spread a thin layer of granulated garden fertiliser over the gravel. Put a 1/4inch (6mm) thick layer of red/ orange clay over the fertiliser. Dry the clay first and crush it into a powder. Then cover that with more gravel.

You put the plants in the gravel and as they grow, their roots hit the clay and fertiliser and they take off and go nuts. The clay stops the fertiliser leaching into the water.

You can smear silicon on the outside of the buckets and stick gravel or sand to them so it is less conspicuous. Or you can let algae grow on them and the containers turn green.

jfcp · Dec 26, 2020

mark4785 said:
I’ve never experienced any issues with the API nitrate testing kit. Double check that it is not out of date and double check you are not using any filter media or substrate that is classed as an ammonia and nitrate remover as all these factors could affect accuracy.

It sounds like something in the tank water is interfering with the result.

As for plants that disintegrate, i’ve only had this happen where a large water change is done that changes the water chemistry sufficiently to kill the plant, i.e with crypt melt and Valis die back. It can also be caused by having inappropriate hardness or temperatures.

You may wish to also look at your KH reading as this is responsible for buffering the pH level of your tank. With a huge uptake of carbonates by the plants and snail waste oxidation, the KH could be becoming depleted which in turn could be making your pH crash. Plants wont like this if it is happening.

thanks.

API kit definitely new; years before any date code issues.

I removed the carbon from the HOB before initial use. Sponge filters NOT the carbon-containing foam type. Can see nothing that should affect NO3 result, which does not mean something isn't.

Don't know how indicative it is, but the substrate looks CLEAN, like new. Malaysian Trumpet snails burrow, and all the fish waste gets reprocessed by them, and gets worked further down into the substrate.

Agree; low Kh reading consistent with low ph, and I am worried about the sudden rise a large water change w/ 7.6 hard water would cause, but in the past, it seemed to help the plants, though the tank ph wasn't so low back then.

I'll try cutting way back on the snail colony first, & other measures to raise the ph.

Naughts · Dec 26, 2020

If you are doing 60% weekly water changes your tank wouldn't have old tank syndrome. Can you add a photo of the tank and plants?
With the API test the instructions say shake for 30 seconds but you need to do it for 2 minutes.
Can you test your tap water pH, KH and GH after it has been left to stand for 24 hours? Sometimes there is a big difference as water companies deliberately temporarily raise pH to protect the pipes.

jfcp · Dec 26, 2020

jfcp said:
thanks.

API kit definitely new; years before any date code issues.

I removed the carbon from the HOB before initial use. Sponge filters NOT the carbon-containing foam type. Can see nothing that should affect NO3 result, which does not mean something isn't.

Don't know how indicative it is, but the substrate looks CLEAN, like new. Malaysian Trumpet snails burrow, and all the fish waste gets reprocessed by them, and gets worked further down into the substrate.

Agree; low Kh reading consistent with low ph, and I am worried about the sudden rise a large water change w/ 7.6 hard water would cause, but in the past, it seemed to help the plants, though the tank ph wasn't so low back then.

I'll try cutting way back on the snail colony first, & other measures to raise the ph.

Colin_T said:
Aponogetons and other plants that have bulbs will usually do well for a few months and then slowly go downhill. This is caused by a lack of nutrients and the plants use the reserves in their bulbs to grow for a bit, then they run out of nutrients in the bulb and slowly die.

--------------------
As for adding potassium nitrate to the tank, nitrates are not found in the wild and whilst terrestrial plants might use it, aquatic plants have to convert nitrates into ammonia before they can use it. There is normally sufficient ammonia in the water from fish food and waste to provide plants with the nitrogen they need.

--------------------
There is usually sufficient carbon dioxide (CO2) in the water for aquatic plants. CO2 is produced continuously by filter bacteria and the fish, shrimp and snails in the tank. CO2 also gets into the tank from the air and is produced by plants when it is dark and they are resting.

If you want to add CO2 to an aquarium, it should be done carefully and preferably before fish are added, just in case it goes wrong and you kill all the fish by adding too much CO2.

When using CO2 in aquariums, you need to buffer the KH to prevent the CO2 dropping the pH.

--------------------
Without seeing pictures of the plants, I would say they are suffering from a lack of nutrients and or a lack of light. Duckweed and other floating plants can reduce the amount of light getting to plants lower in the water column.

Most aquarium plants do well with an iron (Fe) based aquarium plant fertiliser that also contains trace elements.

Aponogetons like a lot of nutrients and your substrate probably isn't providing enough now. As you mentioned, most plant substrates do eventually stop helping plants grow and either need to be replaced or other things added. I used red or orange clay, which I rolled into balls about 10mm diameter and put these in the gravel under the plants. And I added an iron based liquid plant fertiliser regularly. I used an Iron (Fe) test kit to monitor iron levels and keep them at 1mg/ltr (1ppm).
Each week I did a big (75-90%) water change to remove any unused fertiliser and this helped prevent poisoning the fish.

--------------------
Aponogetons and other heavy feeding aquatic plants can be grown in pots in the aquarium. This way you can provide them with more nutrients but trap/ confine the nutrients to the pot and not let them get into the water.

We use to grow plants in 1 or 2 litre plastic icecream containers. You put an inch of gravel in the bottom of the container, then spread a thin layer of granulated garden fertiliser over the gravel. Put a 1/4inch (6mm) thick layer of red/ orange clay over the fertiliser. Dry the clay first and crush it into a powder. Then cover that with more gravel.

You put the plants in the gravel and as they grow, their roots hit the clay and fertiliser and they take off and go nuts. The clay stops the fertiliser leaching into the water.

You can smear silicon on the outside of the buckets and stick gravel or sand to them so it is less conspicuous. Or you can let algae grow on them and the containers turn green.

Hmmm... some fascinating and novel (to me at least) advice there!

One thing I forgot to mention is that I used to have annoying algae growth also, on the filter outlets, on the java ferns, on the hornwort, and that has all virtually disappeared as more and more plants also began to have difficulty, which almost makes me wonder if Phosphorus is an issue, but that sure suggests water column nutrient level is a factor... which doesn't contradict your ideas about substrate nutrients, as both could be factors.

CO2 injection supposed to be such a miracle worker - glad I don't believe everything I read...

Agree I'd have to think about buffering the ph of a CO2 injection scheme before trying it...

I had toyed with the idea of pots with their own special soil. That way, labor is reduced swapping out plants not doing so well... so I think I'll try your clay and fertilizer in pots idea, using small-med polished quartz-veined black stones piled-up around them (that looks good, or is almost unnoticed on the black substrate anyway).

First cut then is clay/fert/ pots....

Thanks!

jfcp · Dec 26, 2020

Naughts said:
If you are doing 60% weekly water changes your tank wouldn't have old tank syndrome. Can you add a photo of the tank and plants?
With the API test the instructions say shake for 30 seconds but you need to do it for 2 minutes.
Can you test your tap water pH, KH and GH after it has been left to stand for 24 hours? Sometimes there is a big difference as water companies deliberately temporarily raise pH to protect the pipes.

eatyourpeas · Dec 26, 2020

Could you be over-filtering and removing nutrients with each water change?

jfcp · Dec 26, 2020

I'll see if I can get plant pics for tomorrow that look at least vaguely like they look to the eye. I didn't this time yet because in the past, trying to get pics of fish, any skin condition looks 10 times worse in the photo.

yeah, with the API, I had re-re read the instructions, done all the shaking and waited for 10,20, 30 minutes, tested water straight from the tap, and tested the dechlorinated, week-old change water.

But you might be right; I did so many tests, not sure I did Kh AND Gh of the water I prepared last week for this week's change (I prepare the change water a week ahead, including aeration, for exactly the reasons you cited, AND because SeaChem Prime is a multi-step dechlorinator - going through multiple chemical steps to eliminate chlorine/chloramine, actually consuming some dissolved oxygen in some of thise steps, so it is advisable to aerate the dechlorinated water before using it in a tank).

jfcp · Dec 26, 2020

eatyourpeas said:
Could you be over-filtering and removing nutrients with each water change?

hadn't heard of "over filtering", but it seems a not unreasonable idea.

I do replenish with a LARGE dose of both Seachem Flourish and Fritz Trace after the water changes, so I should not be nutrient-poor in the water column after a water change...

Colin_T · Dec 26, 2020

Carbon dioxide (CO2) can be useful in aquariums specifically for plants, but you need lots of plants, lots of light and lots of nutrients otherwise you are wasting your time. And if it's not all balanced perfectly, it's turns into a horrible mess.

Try growing them in pots first and if there's no improvement, check lighting and finally, maybe look into CO2. But leave it until last and try other things first. I had a 4x2x2ft planted tank with lots of fish and never used CO2 and the plants did great. I have seen hundreds of other planted tanks that don't use CO2 and they look great. I have also seen planted tanks with CO2 and they look great as well, but they have very good quality gear for the CO2 units and they have all had metal halide lighting.

------------------
Doing a large water change each week will not inhibit plant growth and is beneficial for the fish and plants. The water change removes excess nutrients and prevents overdosing, and lets you start the next lot of fertiliser in a clean system.

I wouldn't worry too much about the filter removing nutrients unless you have carbon in the filter. That will remove some or all of the aquarium plant fertiliser.

------------------
What sort of light is on the tank and how long is it on for?

jfcp · Dec 27, 2020

Colin_T said:
Carbon dioxide (CO2) can be useful in aquariums specifically for plants, but you need lots of plants, lots of light and lots of nutrients otherwise you are wasting your time. And if it's not all balanced perfectly, it's turns into a horrible mess.

Try growing them in pots first and if there's no improvement, check lighting and finally, maybe look into CO2. But leave it until last and try other things first. I had a 4x2x2ft planted tank with lots of fish and never used CO2 and the plants did great. I have seen hundreds of other planted tanks that don't use CO2 and they look great. I have also seen planted tanks with CO2 and they look great as well, but they have very good quality gear for the CO2 units and they have all had metal halide lighting.

------------------
Doing a large water change each week will not inhibit plant growth and is beneficial for the fish and plants. The water change removes excess nutrients and prevents overdosing, and lets you start the next lot of fertiliser in a clean system.

I wouldn't worry too much about the filter removing nutrients unless you have carbon in the filter. That will remove some or all of the aquarium plant fertiliser.

------------------
What sort of light is on the tank and how long is it on for?

Details of light;

Hygger 48 W, full-spectrum LED, I'm using a 16/8 day/night cycle, @ 100% brightness, w/ dawn/dusk feature, and blue night light.

https://www.amazon.com/dp/B086SV5XBY/?tag=ff0d01-20

I checked this light with a spectroscope, and it is "full spectrum"; giving a continuous distribution of hues, with no evidence of emission lines characteristic of fluorescent lamps.

I also noticed on this last water change, that hair algae is now almost totally absent (!). I had a chore every week getting rid of the growth. Considering the amount of fertilizers I have been using, does this perhaps suggest a phosphorus deficiency?

Finally, I had removed all carbon filter elements from the set-up before running anything.

Thanks for the ideas!

jfcp · Dec 27, 2020

jfcp said:
I'll see if I can get plant pics for tomorrow that look at least vaguely like they look to the eye. I didn't this time yet because in the past, trying to get pics of fish, any skin condition looks 10 times worse in the photo.

yeah, with the API, I had re-re read the instructions, done all the shaking and waited for 10,20, 30 minutes, tested water straight from the tap, and tested the dechlorinated, week-old change water.

But you might be right; I did so many tests, not sure I did Kh AND Gh of the water I prepared last week for this week's change (I prepare the change water a week ahead, including aeration, for exactly the reasons you cited, AND because SeaChem Prime is a multi-step dechlorinator - going through multiple chemical steps to eliminate chlorine/chloramine, actually consuming some dissolved oxygen in some of thise steps, so it is advisable to aerate the dechlorinated water before using it in a tank).

Naughts said:
If you are doing 60% weekly water changes your tank wouldn't have old tank syndrome. Can you add a photo of the tank and plants?
With the API test the instructions say shake for 30 seconds but you need to do it for 2 minutes.
Can you test your tap water pH, KH and GH after it has been left to stand for 24 hours? Sometimes there is a big difference as water companies deliberately temporarily raise pH to protect the pipes.

OK, attached are some photo's.

On the far right of photo #1 Overview", is a mass of floating Hornwort that is almost dead: pale tan - to - almost white. Also, hair algae is almost absent now; used to be a real nuisance.

Phosphorus deficiency?

Kyle E. · Dec 27, 2020

jfcp said:
and blue night light.

A little off topic but a quick question....

Can you leave the blue night light on all night and have the fish sleep just fine? Mine has a blue night light that I want to try leaving on but I have never really known if the fish would hate me for it. Also I never knew my gravel glowed in blue light LOL.

StevenF · Dec 28, 2020

jfcp said:
So question #1 would be : Anyone had trouble with the API Freshwater Master NO3 test or the Rotala calculator?

I use rotalabutterfly calculator a lot since are started making my own fertilizer after failing with 4 separate purchased fertilizers. I doublecheckec your 1.85gram dose aud it appears to be correct. I can only think of two explanations for your zero nitrate readings with a probably good test.
1. you don't actually have KNO3.
2. you have bacteria in your tank converting the nitrate to NO3 to N2 at a very rapid rate.
I don't know what else would cause your situation.

your symptoms are 100% consistent with nutrient deficiencies. but you have only looked into 2 deficiencies NO3 and PO4. That is 2 out of 14 possible deficiencies excluding CO2, and light. Your plants should grow fine with 10ppm NO3 and 1ppm PO4. It is much more likely that you have micro nutrient deficiency such as zinc, copper, molybdenum. Your GH is high enough that that I wouldn't expect Calcium or magnesium would be a problem.

CO2 was once thought to be the cause of most aquarium problems but that has been proven to be false. most of the time it is micro deficiency issues or Ca, Mg, or S deficiencies.

jfcp said:
I have been using SeaChem Flourish and Fritz trace elements all along, but even increased doses make less and less, if any difference now.

Can you provide me with any information of the Fritz trace fertilizer? I am not familiar with it. Can you provide a list of the ingredients or guarantied analysis from the label?

I personally used SeaChem Flourish Comprehensive for some time before throwing it away. I know this will surprise a lot of people but Comprehensive is not a comprehensive fertilizer. If you follow the manufactures dosing ecomentations you will be deficient in calcium, magnesium, zinc, copper, molybdenum, and nickel. with barely enough NO3 and PO4 to grow anything. Flourish comprehensive assumes your tap water and substrate will provide all the some or all of the nutrients the bottle lacks. But each utility is using different water sources, and many people use a wide verity of substrates. So sometimes flourish works and sometimes it does't. Even a nutrient rich substrate is not likely to have enough to last an entire year. In your case you ran out in a couple of months.

In my case I started my aquarium with RO water and an inert substrate. The worse possible combination. I gave up using purchased fertilizers after trying 4 fertilizers. And instead made my own macro and micro fertilizers. It is not easy but it definitely worked very well.

You might try TNC fertilizers. According to the information Rotalabutterfly it is a close match to what is in my micro fertilizer fertilizer. Unfortunately I never tried TNC in my tank. And as I said earlier 10ppm NO3 (KNO3) and 1ppm PO4 should work for macros. As for the remaining macros (calcium, magnesium, and sulfur I think your tap water has those. If not a GH booster would help.

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