Question on Nitrate

Thank you for all the help! I'm a little worried about adding any fertilizer since all my plants other than the wisteria are doing well. Will the addition of fertilizers harm my tetras?


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My friend and mentor Byron points out somewhat old school thinking in regards to tank pollution. Uneaten fish food, fish and plant waste, urine, respiration's would seem to accumulate nearly unchecked. However, there is a plethora of other beneficial bacteria that decomposes and breaks this material down into fairly harmless compounds.
The Walstad method proved that with a balance of growing plants to livestock, water changes became counter productive by removing nutrients that the plants would otherwise need/use.
But almost nothing illustrates the point more than the use of Seachem Excel (or Metricide) in planted tanks, The main ingredient in these products is glutaraldehyde that is used as a liquid carbon source for plant growth, sometimes instead of CO2. However, in reality, glutaraldehyde is a toxic chemical used to sterilize heat sensitive medical and dental equipment. This toxic chemical is added daily to thousands (maybe many more) of fish tanks daily and yet there is no apparent negative impact on livestock (unless severely overdosed). The reason is that this material (just like excess food, fish and plant waste) is decomposed into relatively harmless (in this case beneficial for plants) compounds. If the old school thinking was accurate and these substances just built up, the use of Excel or Metricide would sterilize (kill everything) in the aquarium in short order!

Now this is not to say that routine weekly water changes are not beneficial, because they are. Nature refreshes 'fresh' water all the time with rain.
I have stood at the edge of Niagara Falls marveling at the millions of gallons of fresh water flowing between the Great Lakes every minute of every day.

As far as the frequency and amount of required water changes, every tank is different in plant bio mass, stock level, eco system maturity and filtration. As a general rule for most tanks, I think 20% is a good target with 50% as a maximum....with caution on temperature and water conditioning.

Tank on,
-Mike
 
I appreciate the advice, however I don't really want to limit my water changes. My fish are doing excellent with the schedule they're on and I assume the low nitrates is a good sign the tank is doing well. Other than a light dusting of diatoms on a few plant leaves, I virtually have no algae and my bladder snail population is well in check. I can't see how too great of a water change can be a bad thing, unless I'm destroying my biological filter, which I'm not.


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I always change 50-60% a week, I've done it this way for years with no adverse effects, my young fish grow like they're on steroids, you have to remember that water changes don't only replenish minerals etc, they remove hormones that are secreted by fish.
 
Before commenting briefly on some misconceptions mentioned since my last post on water changes...to the question of fertilizer harming your tetras, generally no unless they are overdosed to excess. However, a basic concept in an aquarium with fish is to limit all additives to only those that are essential, regardless of whether or not they may be directly harmful to fish. We must remember that water--and with it, all the substances we add to the water--is continually entering the fish primarily by osmosis through the cells, and this water is then processed by the kidneys, enters the bloodstream, affects other internal organs, and so forth. Fish are not exposed to any of these chemical substances in their habitat, so their physiology has to deal with them as "foreign substances." While this may not immediately kill the fish, it has the likely effects of weakening it, causing stress, and perhaps shortening the lifespan. All because the fish has to somehow react and deal with these substances. So, it is better to keep them to the absolute minimum.

I recently had a problem in one of my tanks, and after months of tests and experiments with on-going advice from some of the most knowledgeable individuals in this hobby, including microbiologists and biologists, I got to the bottom of it. But along the way I learned that I was adding more plant additives than necessary, and these were in fact contributing to the issue. I try to learn from my mistakes, and I have since reduced the additives by more than 3/4 with no injurious result to the plants (actually the opposite, interestingly) and I know the fish would thank me if they could. And in a sense, by their recovery and behaviours, they have done so.

Which leads me to the misconceptions about water changes. Diana Walstad's method requires minimal fish load and heavy plant load, and that sets up a different environment than what most members here have in their aquaria. I know I certainly have more fish in my tanks than she does, probably by two if not three times from the numbers I have read in her book and columns. Water changes removing plant nutrients is misleading, unless we have the data. Algae certainly is somewhat thwarted by more water changes, so it could be assumed that "nutrients" are being removed, but if so the question is just how much and how necessary for the plants were they to begin with. It is also possible that the water changes are having some other effect that thwarts algae.

There are still compounds entering the aquarium water continually that no bacteria and no filtration can remove. And the fact that fish have been shown to be more responsive (benefit) by more water changes cannot be argued. The long-term effect of all this is the real problem. The more water changed, the more stable the aquarium will be.

Byron.
 
Cboatman, my pennies worth is to stick with your water changes if it's keeping the tank healthy, I usually change 30-40% during my weekly change. As for adding fertilisers, I have used liquids in the past with no ill results to any fish (including tetras), but I now tend to stay away from stem plants like your wisteria and go with rhizome plants (Anubias, java ferns etc) and rosette plants (swords, crypts etc) as I find these easier to work with and harder to kill. For my rosette plants I add ferka rosette root tabs to my substrate every few months, plants love it and seems to have no effect on the fish. Hope this helps.
 
I saw no misconception. My point was merely that in the established eco-system aquarium large water changes become less necessary due to the biology that continually decomposes organic waste into harmless compounds and plant usable nutrients. I don't fully buy in to the Walstad method, however as an organic vegetable gardener for 30+ years, I see the merit in growing plants organically.
HOWEVER, It is true that in many tanks such as fish only tanks [some that are only glass, water, and fish], immature tanks [planted or not], way over stocked tanks, etc. large water changes are extremely crucial since there is insufficient biology to effectively process and convert the organic waste.
 
I agree with all of that, but we are not dealing with vegetables using organics in a garden but fish living in a confined volume of water. There are still substances accumulating that cannot be removed by any method except a water change.
 
I do a 50% water change weekly and have observed no harmful effects. The only fertilizer I recommend to is Seachem Flourish Comprehensive. It contains all the elements plants need to grow and all are in forms that can occur naturally in rivers and lakes. If does according to the manufactures recommendations it will not harm fish, shrimp or snails. I also have black neon tetras in my tank.
 
I agree with all of that, but we are not dealing with vegetables using organics in a garden but fish living in a confined volume of water. There are still substances accumulating that cannot be removed by any method except a water change.

Ah, but at least a planted tank is an aquatic garden in a container....and the same basic rules of nature apply. But then again, if folks feel they need massive water changes, so be it. However, under some circumstances, large water changes can severely stress fish as water chemistry can dramatically change.
The real key is to religiously do water changes routinely w/o fail. I think too many times for some, as the novelty wears off, tanks get neglected in this regard and fish suffer.
 

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