Nitrate Reduction: The search for the holy grail

Nobody likes doing partial water changes... okay some do but we'll talk about those weirdo's later
Many hobbyists will go on a quest for lower nitrates like a search for the holy grail. As recent post reminded me.

This also reminds me of the zillions of dollars manufacturing plants spend on the latest fads for increased production with higher quality (Quality circles -> the Deming philosophy -> ISO 9000-9001 -> Six Sigma...) But I digress.

With nitrates in my well water, I too endured a period of what I've called My Nitrate Fight.
I tried low flow filters with commercial bio-media that promised 'micro pores' like live rock to allow culturing of anoxic/anaerobic bacteria to process nitrate into harmless nitrogen gas. I've done deep sand and my most recent attempt was Dr. Kevin Novak's Anoxic Biocenosis Clarification Baskets.

In the end, most fresh water aquariums simply are too highly oxygenated to provide the proper environment for anoxic/anaerobic cultures large enough to provide a serious reduction in nitrates. The time honored methods of Lowering Aquarium Nitrates still hold true.

Oh from time to time we'll hear stories about tanks that get few, if any, water changes with zero nitrates. I can't say these are 'fish tales' but sometimes I question the test results. Or maybe there are very few fish in a heavily planted tank. Or maybe there's some other special case, but these tales are exceptions rather than the rule.

I invite you for a deep dive into Filtration and Water Quality.

Hi Abbysdad, I'm one of those people who advocate smaller rather than larger water changes because I find that large water changes can up the balance in a tank. My tank is overstocked by about 10% and I change only 15% per week. I always use a gravel vac and I clean my Juwel Bioflow filter every 6 weeks - just the top sponges, the lower bio media I rinse gently every other time, so 4 times a year
My nitrates are very low despite coming out if the tap at 35ppm and I attach pictures to show what I have tested this morning, using tap water that has stood for several hours.
As you can see the test confirms the water company's claim of about 35ppm whereas my tank is almost zero, despite having had a 15% change yesterday. Hopefully you will agree that the results are genuine and that this isn't a fishy myth!
What do I do? Well, the tank is heavily planted with vallis and ludwigia plus a few crypts. At different times different plants have prevailed but at present vallis has taken over and what was for a while a quite delicate 'tiger' spiralis suddenly grew to gigantic proportions with 6 foot leaves nearly an inch wide! To be sure it blocks too much light and I do do try to thin it occasionally but I always hate pulling out healthy plants! I have some salvinia too, which took a while to get going because the fish would pick at it, but now I pull it out by the handful - probably because the fish no longer see it through the vallis! Anyway, you get the idea, I have a lot of plants, but if they are using up the nitrate they must be taking it up directly, rather than by absorbing ammonia because my tap water contains so much. Before I had the floating plants the level was a little higher at around 5-10ppm, so they have made a difference.
The Juwel Biofilter is designed to have a lower flow through the lower part where the bio media goes. I use Seachem Matrix and I like to think that by leaving it largely undisturbed, some nitrate reduction at least occurs there.
When I start a new tank I try to use as much existing media and water from an existing set up. It still takes a while for nitrate to stabilise at such a low level and it is very difficult to say whether this is because the plants take a while to establish, or whether the bio filter bacteria do. It's probably a bit of both, however, one thing I have found is that when nitrate reaches over 20ppm, my plants suffer, so I end up in a catch 22 - persistent higher nitrate because the plants won't grow, but the plants are being stunted by high nitrate. I overcome this by using a nitrate removing resin such as Nitragone which is very effective at rapid removal. Using this a couple of times over a few weeks gives the plants time to take hold, after which it is no longer required.
At one point my plants started to suffer and I initially suspected that my low water change regime might be causing high phosphates. However, I bought a test and found that I actually had zero phosphates, and the problem was therefore a lack of these not an excess! To solve it I now add phosphate to keep the level at 1 - 1.5ppm. I use a fert without nitrate but as far as I know all the ones without nitrate also come without phosphate. I used EasyLife to prove that phosphate deficiency was the problem, but that is expensive, so I now make my own for a fraction of the cost (thanks YouTube!).
Hope this has helped!
My tank lights are off at the moment and I will be going out later, but if I get a chance I will try to post some pictures.

OK, I managed to take some pics. This is a 260l tank with 15 medium sized fish between 4 and 6 inches plus a group of 5 pygmy chain loaches, fully grown at about 2 inches. So I reckon about 10% overstocked. The last fish introduced were the Alestes Tetras about 18 months ago. As you can see, lots of plants - actually thinned out 2 days ago.

@raylove, perhaps your tank is an exception to the rule. From a front/side view the tank doesn't appear to be heavily planted, but from the top view , the Jungle Val has extensive leaf growth. Your test result photos are a bit confusing as I see high nitrates, low/no nitrates, then high and low/no nitrates. I guess from your text I could presume that the high nitrates is your source water and low/no nitrates is your tank water?
Even with my many efforts in my nitrate fight, I have never personally had a tank with fish with low/zero nitrates. So forgive my skepticism and good for you!

AbbeysDad said:

Even with my many efforts in my nitrate fight, I have never personally had a tank with fish with low/zero nitrates. So forgive my skepticism and good for you!

Click to expand...

It certainly does depend upon the qualities of your source water and I've clearly been blessed, enjoying zero nitrate readings in all 3 of my tanks. That said, all are very well planted, with fast-growing plants and floaters.
Of course, I also accept that all tanks with livestock will always have some measure of ammonia, nitrites and nitrates, ideally at levels too low to register on whatever sticks and/or liquid tests we use.

Sorry if my test result photos were confusing. Yes, the high nitrate result is the tap water. The water company says the supply is 35ppm so the API test comes out as expected at 30-40. The 'virtually zero' result is my tank water. I then photographed the two side by side to illustrate that the tests been done at the same time. I am aware that if the testing agent isn't shaken sufficiently, a false reading of zero can be produced, so by doing the tap water test first and getting exactly the expected result, I was looking to prove the accuracy of the tank water test.
Yes, with most of the plant mass now across the surface the tank doesn't look as densely planted as it is. The ludwigia has reduced due to less light getting through and I recently removed 90% of the crypts that covered the floor as they were making it look darker still. I took out a bucketful of vallis and salvinia two days ago so you are seeing it at it's most sparse!

@raylove and @Bruce Leyland-Jones - Good For you two!

I have never had a problem with nitrates in any of my tanks.

What was the nitrate level in your source water? If that was low you wouldn't have the same problem as those people who have high nitrate in their source water.

Essjay said:

What was the nitrate level in your source water? If that was low you wouldn't have the same problem as those people who have high nitrate in their source water.

Click to expand...

No argument there, which was why I specifically stated "

Bruce Leyland-Jones said:

It certainly does depend upon the qualities of your source water and I've clearly been blessed,

Click to expand...

One issue I've become way more aware of is the variance in water sources, (and subsequent quality), amongst US members in particular.
In the UK, I've lived in 8 places and only in one, an out-of-the-way country cottage, did I have a non-mains supply and that was direct from a granite-filtered spring.
Obviously, being dependent on well water creates a whole new set of challenges for fishkeeping.

We've only ever lived where there was mains water.
We are lucky with our water as well. The water company gives the average as 2.642 ppm (Nitrate-NO3 scale like our test kits) and the API tester gives between 0 and 5 ppm.

More and more I/we hear stories of high nitrates in source water, most notably in agricultural areas.

I live across the road from a 95 acre farmers field. Years ago I struck up a conversation with a farm hand that told me they wouldn't be able to grow much without a LOT of (chemical) fertilizer. The land (I suspect was/is leased) changed to a different dairy farmer that just spreads manure. Although the air takes on a different level of 'freshness' a few times a year (sprayed from tanker trucks these days) the nitrate levels in my well water is thankfully MUCH lower these days!
So I've never had to use a conditioner for chlorine/chloramine for my well water, but have pre-filtered to remove ammonia/nitrates. (btw we only drink bottled water)

Clearly keeping tank nitrates low is a challenge/problem for hobbyists with high nitrates in their source water. However, even setting high nitrates aside in source water, the 'search for the holy grail' also lives on with hobbyists that would prefer some magic bullet to reduce or eliminate the need for routine partial water changes in an attempt to achieve and maintain a low/no maintenance aquarium.
I think in part this may be tunnel vision as although we may use nitrates as a guide, tank nitrates keep bad company with other pollutants like phosphates, pheromones, and heavy metals to name a few. And since plants and fish use minerals in the water, the reduction/elimination of partial water changes in favor of top offs for evaporation not only increase the potential for greater concentration of some pollutants. but also a potential deficiency in necessary minerals.

Of course, plants come to the rescue as plants, especially fast growing stem and floating plants, use nutrients (aka pollution) for growth, converting these into plant plant tissue later removed with trimming. The heavily planted tank with a few fish, proper feeding, and other decent tank maintenance will require a much lower frequency/volume of fresh water changes. So in some cases, there can be a very low requirement for the frequency/volume of partial water changes. I'm doubtful that partial water changes can be eliminated altogether and there's really no substitute for fresh, clean water.

For most hobbyists, in addition to good biological filtration, plants, proper feeding, and good aquarium maintenance, the 'holy grail' is likely the routine, periodic, partial water changes of sufficient frequency and volume to maintain a high water quality. "The solution to pollution is dilution". And with no plants, overfeeding, and/or poor tank maintenance, the partial water change makes ALL the difference in the aquarium world.

(Whew, he does go on and on! )