My information comes from Kmuda on Oscarfish.com, he has tried this system as others on the sight and did not find this to be a practical application for fresh water fish keeping. Please feel free to register and ask him for more information.
high nitrates - always!!! PLEASE HELP
- Thread starter Aglaia
- Start date
Ah, he's utilizing planktonic bacteria to reduce nitrate and he was having problems removing the bacteria without skimming. It's another option, but I've never seen it done in freshwater. He goes so far as to say that "you can't skim in freshwater"...lol. Admittedly, it's not as easy as saltwater but I'm about 50 ft. away from 7 fractionators running on freshwater systems. You can tell he reads a lot but his understanding is basic, presumably why he asks for help from the "salt water guys". Primary articles will tell you that this has been done for a long time.
I try to keep things simple. Consistently high nitrates mean that you are simply not changing enough water for your bioload. You can fix this (I am not wading into the dinitrification debate, just responding to the OP issue and being realisitic) by increasing water changes or decreasing your bioload. I would suggest both, initially. Your stocking seems light, so reducing your bioload is not reducing the fish. But it seems you are feeding waaaaaaay more than necessary as others have noted, and also what you are feeding is messy. I would second the suggestion of moving to a nice high-quality pellet with frozen being a treat a couple of times a week, no beef heart. Feed much less per feeding, just a tiny bit at a time to ensure it all gets eaten before it hits the gravel, and skip feeding altogether every few days. So change your habits, increase water changes, and stay on top of keeping your filters clear and gravel vacuumed. That will fix it for sure.
This is an excellent point. Many people change more than this at one time. I'm sure I've removed as much as 75% on occasion. If you don't want to do more than 50% at one time, then you can do 50% twice as often.
I like to think of it this way: 50% per week might be the correct amount if one obtains the correct results, that is, the nitrates are kept very low (below 20 ppm.) If the results are still too high, then either other variables have to be fixed, or the frequency or size of the water changes has to be increased.
Many people have already detailed other options besides WC, so you can make some other choices if the current WC pattern is where you want to keep it. Here are ones I recall others posting:
1) reduce stocking levels
2) add appropriate plants (pothos is an excellent choice)
3) change type of food (high protein to lower protein, or less "filthy" foods")
4) feed less
5) improve maintenance (vacuum / filter cleaning, etc.)
6) add nitrate adsorbing materials (e.g., purigen)
Doing larger WC or more frequent WC is just one more option, not the only option. In the short run, larger and more frequent WC will probably have the most immediate impact, but it's not the only long term solution.
There is technically no "maximum" water change. When you get a fish at the store, bring it home, and put it in your tank it gets a 100% water change. Just make sure that your fish are acclimated to the new water in an appropriate timespan. The new water also often needs time to exchange gases so that the fish don't suffocate, become narcotized, get the bends, etc... The largest changes I've seen in a day are about 300%. I wouldn't recommend something like that as a general maintenance routine, but I have one big hybrid cichlid that gets 80% changes. I just add the new water slowly, sometimes stopping and letting the fish acclimate for a little while as well. Just be conscious of how quickly you're changing the tank's water parameters.
Not to beat a dead horse, but having deep substrate is also known to help mitigate nitrates by providing a home for denitrifying bacteria. For more info look up "deep sand beds" in aquariums. 2 out of the 3 reef tanks I run have "deep sand beds" (3") and have 0 nitrate at all times. The third has 1" of gravel (crushed coral technically) and nitrates creep up to about 40ppm with my routine maintenance. Any substrate that gets water flow but has enough stuff (physical stuff and heterotrophic bacteria) around it so that the oxygen gets used up before penetrating the inner area will work for denitrification. Even a bag of SeaChem "DeNitrate" in the filter could make a difference once the substrate is colonized. All that the store-bought reactors are is a chamber, containing media, with a low-speed pump attached.
Unfortunately there is no product that will actually remove the nitrates themselves (paraphrased from SeaChem's website). The closest you can get is something that removes ammonia and nitrite, lowering the nitrate produced. Examples would be carbon, protein skimmers, purigen, etc...
Not to beat a dead horse, but having deep substrate is also known to help mitigate nitrates by providing a home for denitrifying bacteria. For more info look up "deep sand beds" in aquariums. 2 out of the 3 reef tanks I run have "deep sand beds" (3") and have 0 nitrate at all times. The third has 1" of gravel (crushed coral technically) and nitrates creep up to about 40ppm with my routine maintenance. Any substrate that gets water flow but has enough stuff (physical stuff and heterotrophic bacteria) around it so that the oxygen gets used up before penetrating the inner area will work for denitrification. Even a bag of SeaChem "DeNitrate" in the filter could make a difference once the substrate is colonized. All that the store-bought reactors are is a chamber, containing media, with a low-speed pump attached.
Unfortunately there is no product that will actually remove the nitrates themselves (paraphrased from SeaChem's website). The closest you can get is something that removes ammonia and nitrite, lowering the nitrate produced. Examples would be carbon, protein skimmers, purigen, etc...
Chill out.
I missed that. If I had the option of deleting my post right now, I would. I also was not aware of the food the OP was using. It seemed he was just using flakes or the basic stuff.
Purigen does remove nitrate pops. I've tested it in my 600 gallon system before i added pothos. Nitrates were 80ppm. Added purigen and they dropped to 40 in two days on a tank with massive bioload. No water changes. If it only removed ammonia and nitrite, my nitrates wouldn't have dropped it only would have slowed their progression.
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