Balanced Ecosystem? Rules of thumb?

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CGGorman

Aquarium Advice Activist
Joined
Dec 21, 2005
Messages
196
Location
NW Ohio
Is there a rule of thumb for stocking levels to help create a balanced aquatic ecosystem (flora vs. fauna vs. microorganisms)?

I've got a planted 55 that I would like to turn into a fairly self sustaining ecosystem. Obviously, I would feed the fish, provide heat and light, and run mechanical filtration (and keep the water topped off). Beyond that, I would like the nitrogen, CO2, and vitamin/mineral cycles to reach an equilibrium. Is this a nirvana that I will never reach?

Currently, the tank is about 1.5 wpg and has a quartz substrate with a Fluval 304. It's a very mature tank and hasn't been torn down in at least five years. Water parameters are stable, fish are healthy, but plants are sluggish and fish waste builds on the gravel. I vacuum and top off about once a month, so that works out to about a 10 or 20% pwc per month.

See my gallery for some pictures...

Current fish stocking is three 1 1/2" peppered corys, eight 5" Giant Danios, and a single 13" common Pleco. No snails or scavengers. That works out to about 1" per gallon.

Current water parameters...never used to test until I started getting frustrated with the plants. I now know my Nitrates are sky high. WAY over 160, which is where the test tops out. Doesn't seem to bother the fish (who spawn several times a year). Regardless, I've got a sachet of Nitra-zorb in the filter to help mitigate that. Need to recharge it, I think. After a week in the filter, the level is still over 160. pH is stable at 6.6. Nitrites are zero. Ammonia is zero. Still waiting to test Iron, Phosphates, gH and kH. Any other tests I should perform?

I'm pretty new to planting...
Current planting consists mostly of Aponogeton, grown from "wal-mart" bulbs. They started out going gangbusters, with floating leaves and flowering, but have since shriveled down. They now seem stable with little/no new growth and algae on most of the older leaves, which I prune off. All the stems are about 2", so the mass of the growth is in the lower 1/3 of the tank. NO CO2. I'm just tipping into fertilizers. Tried Marc Weiss "natural aquarium vital" with good results at first, but it doesn't seems to do anything now. Also tried some Seachem "Enhancer: NPK" liquid ferts, dosed according to the directions. Didn't do anything. I'm now getting together a set of test kits to get a handle on what my water looks like. I'm not looking for wild growth out of this low-light tank. I just want healthy, stable plants.


I've got one sword that seems stable with little new growth.
I've got two vals that are struggling. Again, they also have algae growing on them. I prune off the ugly bits, but I'm not seeing any new growth.
I tried floating water lettuce, and it yellowed badly and died after about a week.
I tried Banana plants and they slowly withered and died, too.


After those failures, I decided to get serious. I went out and bought a few books on planted aquaria and now I know that I don't have enough light for many of the plants that my lfs carries. Since I've got so many Apons, I'm trying to keep them going. I'd hate to pull them out and replace with java fern or crypts...but I may have to.

Just to reiterate, the fish are great. Pleco has been in this tank for about ten years and most of the Danios are seniors at 5+ years old. They have excellent color, shape, and activity.

How do I get a handle on the plants, algae, and (what I consider to be) excessive mulm (is that the right word?) on the gravel?

Am I over or under stocked with fish? I know it used to be about 1" per gallon, so by that rule I'm right on. Does that change with planting? I assume it must. My gut tells me I need more fish to balance the plants, but my solid waste already seems too high and adding fish will just make it worse, right?

Does that mean I need some scavengers to further refine the solid wastes? Or do I simply need better gravel-level circulation? Or do I need to stir it into the gravel?

When trying to reach a balance, I assume I determine fish stocking based around planting...correct? Once I determine how heavily planted I want the tank, then I need to add fish and scavengers until it's balanced? How do I know when I've reached that point?



Sorry for the long, detailed post. Feel free to suggest any reading I should do or other places I should look. I've looked through the commonly available titles and don't really see anything as in-depth as I need...
 
Diana Walstad's Ecology of the Planted Aquarium is the book you seek. It goes into very specific detail on how to create an almost completely self-maintaining system.

Stocking levels are quiet low. The book is rather scientific, but judging from the questions you've been posting, I think its exactly the sort of reading you would enjoy.

I myself like to keep things light and fun, and there's nothing wrong with either philosophy :)
 
http://naturalaquariums.com/ is a site that may be of interest to you. Your nitrates are very high, being 4 times the max recommended, and 10 times what I would prefer. If the sword plant has been in the tank for more than a year, it has probably formed a bulb, and will not show any appreciable growth until you remove it. It can be carefully twisted off or cut off. New plants will sprout from the bulb. I think you need to change more water. The 1" rule is only a guide line and the 13" pleco throws it right off the scale. To put it in perspective, that 13" pleco is not equivalent to 9 male guppies, in body mass. If your interested, there is a thread started by BrianNY disscussing the 1" rule on this forum. To cope with the algae and remove some of that nitrate, try some hornwort. It grows like crazy when you have lots of nitrate, and will provide some shade to slow the algae.
 
Your high nitrate levels say that you are overstocked. Suggest you increase the plant load with light appropriate plants. In addition to references above, check out TG and Billsgate's successful natural aquariums, too.
 
I would recommend either do larger water changes, more frequent water changes, or both to get you Nitrates down to better levels. This will help reduce the food for algae and as a result should help out your plants.

Water changes should be taylored to your tank, if they're continually sky high it means you're current water change schedule isn't keeping up with your bioload. Once you get the Nitrates down to at least 20 - 40 ppm, you can play with the frequency/size of your water changes to determine what schedule your tank needs.
 
CGGorman said:
I vacuum and top off about once a month, so that works out to about a 10 or 20% pwc per month.
.......
Current water parameters...never used to test until I started getting frustrated with the plants. I now know my Nitrates are sky high. WAY over 160, which is where the test tops out. Doesn't seem to bother the fish (who spawn several times a year).
.......
Does that mean I need some scavengers to further refine the solid wastes? Or do I simply need better gravel-level circulation? Or do I need to stir it into the gravel?

During this month, how much water evaporates from your tank (estimate)? How much water are you vacuuming out of the tank? You mention total 10-20% per month but what of that 10-20% was actually removed by vacuuming? Anything that evaporates does not count as a PWC. All that is happening is the nitrAtes and other pollutants present in the tank are concentrated

Next thing I would do is test your tap water for nitrAtes. If its zero or very low, my next recommendation will be a very good thing to do, if nitrAtes are high, its probably not worth it.

OK, so your tap nitrAtes are zero or very low, what would really be a good idea is to do a serial dilution. This is where you take 1/2 the normal amount of tank water and mix it with 1/2 of some other water (I'd make up a cup or so of dechlor'd tap water that you let sit out overnight so it doesn't mess with results). Use dixie cups or other small disposable cups for this since you need more than the 5ml for your test (I'd take 1 full dixie cup of tank water, and mix with another full dixie cup of the other water, and go from here). Essentially what you are doing is cutting in half the amount of nitrAte in each successive cup, so that you can get a reading that is in range of the kit. Then when you finally get an acceptable value you count back how many dilutions you had to make and double the number for each dilution.

I'll give a quick example:

You start your test, and the first 4 tubes read too high to get an accurate value. Your 5th tube though shows 10ppm nitrAte. To find out how much nitrAte you ACTUALLY have in the tank water you:

10ppm nitrAte in the 5th tube, means you had 20ppm in the 4th tube, means you had 40ppm in the 3rd tube, means you had 80ppm in your 2nd tube , means you had 160ppm in your first tube (this was the one that you mixed 1 to 1 with tank and tap water). So this means you have ~320ppm nitrAte in your tank water.

This test is as accurate as your measuring is, and you don't have to measure each dilution. As long as you remember how many dilutions you made, you could jump right to the 4th or 5th dilution and do a nitrAte test with that one. Then just double that number for every dilution you did and you'll get the value in your tank.

I'd do this test FIRST, because it will let you know about how many PWC's you need to get back to "safe" levels. I say "safe" because a long time ago I had a goldfish and a pleco in a 10gallon tank for SEVERAL YEARS and never did a water change. I would just top off and probably overfeed, and never do a gravel vac, and the fish lived for a long time. It was probably horrible conditions but I didn't know better at the time. I bet those nitrAte numbers would rival yours. :oops:
 
I ordered the Walstad book. Looking forward to the read. Also ordered two of the Amano picture books for ideas on aquascaping my 70.

I should get the rest of my test kits this week. Once I have a complete picture of my water parameters, I'll start taking corrective action.

I got to test the gH and kH this weekend. gH is 240ppm and kH is 80ppm. Need to get that kH up. I guess I need to visit Greg Watson!

Good idea about the serial dillution. I'll try that, but frankly I'm not terribly concerned about the exact current level since it's obviously too high. I'll just keep bringing it down until it's under 30.
 
Oh, Hornwort. I've started looking at all the local shops.... Will get some when I find it.
 
Walstad's book may mention this too, but if not, there are ways to build de-nitrafying coils that'll reduce nitrate buildup too. more common in SW setups, but should work in FW too from my basic understanding of the construction.
 
My tap is nitrate-free, so better water changing habits would reduce the problem. My concern, though, is that water changes really only treat the symptom. Where do the high nitrates come from? What does Mother Nature use to eliminate them and how can I impliment that in my captive "biotope".

I don't care if my tank is a representative cross-section of any of nature's actual regional ecosystems, but I would like it to function as a more-or-less self-contained environment.

Like Malkore, I want to keep it light and fun, but I need the background first. I've been doing it wrong for 20 years and now I want to correct my mistakes. My goal is learn enough so that I can stock the tank to require minimum maintenence with maximum health. Now, I'm not talking about a 99% efficient "biosphere"-type setup, but I also don't want to have to do weekly 50% water changes and daily fert. dosing...
 
In nature, there's a layer of muck at the bottom of lakes and streams several inches below the floor/bed. This anaerobic region is what breaks down nitrates into nitrogen gas (and oxygen I would presume).

I know Walstad discusses layered substrates, that probably eventually form this good kind of anaerobic zone. Combined with her ultra low stocking scheme, it would explain her balanced system.
 
Nitrate removal is still through plants. You will learn that her system uses feeding, soil, and tapwater (top/off) as the primary sources of nutrients for plants. There is a chapter on carbon from decomposing organic matter. She has numbers on all this from control tanks and comparisons to specific plant habitats and numbers from nature. I gave up my Walstad tank but still find her philosophies on plants as filters relevant in all light levels, and her arguments and numbers in the book persuasive, though often over my head.

Should you find the idea of replacing your substrate unappealing, there is always the traditional low-light set-up using regular trimming and water changes for nutrient export, and you do not need to regularly change as much water as some high light methods. If you have trouble finding Hornwort at your LFS, try getting some of it and/or Anacharis from a plant nursery with a pond section. Both are uptake machines that are not demanding of light or dosed nutrients (carbon, trace, etc). (Might have luck with the barter/trade section on AA as well.)

No matter what method you use, you need a lot more plants. I think you will do fine fwiw. Good luck.
Joe
 
I lieu of the Hornwort, which I can't find locally, I found some Anacharis on sale yesterday and bought four bunches (everything they had) @ $0.88/bunch. Also picked up a couple (4) Otos to help deal with the algae on the leaves. Those sure are some industrious litlte suckers (pun intended).
 
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