15 replies to this topic

[Skuts]

I did a nitrate test on my tank before a water change it came up at about 10ppm I did my usual 50% weekly water change and re tested for giggles i noticed that the nitrate came down to about 5ppm, my question is should I be aiming for 0 nitrate or is the whole idea of a water change just to lower it back to a more acceptable level??

Thanks in advance

[Neakit]

If it is a marine tank i would say aim for 0, if it is a fresh water i would say your fine.

[Juls]

For freshwater anything under 10 is very good, under 20 ideal, under 40 ok for larger non sensitive fish. Above 40ppm can lead to long term problems on some less hardy fish there internal organs can begin to fail and or immune systems become compromised and fish can succumb to infections or disease.

Most african cichlids and large American cichlids seem to cope with high nitrates well.

Rare corys, L numbers, small community fish, wild discus or altums, apistogrammas ect tend to be less tolerant to high nitrate readings.

0 is the ideal reading, but unlikely.

Only tanks I have managed 0ppm long term where well planted shrimp tanks. (despite huge stocking ratios).

This is partly because the plants take up the ammonia directly so the filter does not get a chance to convert it to nitrate.

Juls

[Cawdor]

in freshwater anything around 20ppm is fine.

Edit: ninja Juls

[bigjohnnofish]

a lot of fish will adapt to higher nitrates as long as its been a slow increase - not a big jump caused by big ammonia spikes....

and then the stupid thing is you take these fish and put them into a tank with zero or low nitrates and they suffer....

so in theory most fish will adapt to most situations... but theres always some fish that wont.... you just have to learn which ones will and wont cope with higher nitrates....

[Blasfish]

Hi,

I wish I would have your nitrate readings.
We have a 6 foot fish tank with several African and a couple of American cichlids. I just can't get my nitrates down. I did a 50 percent water change yesterday and tested the water straight after it and it was over 80ppm!!!
I already reduced feeding weeks ago and our tap water has pretty much 0 nitrates. Not sure what to do.
Should I get live plants? All the plants I had so far always died.

Any advise??

Edited by Blasfish, 11 April 2011 - 03:41 PM.

[Neakit]

more water changes or invest in a denitrator.

[Cawdor]

weekly waterchange of 50% until nitrates are at normal level ~20ppm. feeding once every couple of days, only a pinch of food. Adult fish can handle going without daily feeding easily when they are healthy.

[golden_dase]

Does anyone test the "tapwater" before they add it to the tank?

[Juls]

If your nitrates are getting up to 100ppm, suggest bagging all the fish, 100% water change and reacclimatize the fish like you just bought them.

You filter may also be holding nitrate solids, if you find your nitrates jump straight back to 20-30ppm then filter and gravel needs cleaning.

Unplanted tanks always need more water changes, and canister filters tend to build up nitrate solids over time dissolving them back into your tank water.

If I ever setup a big cichlid display again I will use a sump and fw refugium system better to use up the ammonia before the filter has a chance to convert it to nitrates.

Juls

Edited by Juls, 11 April 2011 - 09:17 PM.

[Cawdor]

If I ever setup a big cichlid display again I will use a sump and fw refugium system better to use up the ammonia before the filter has a chance to convert it to nitrates.

Hi Juls, can you elaborate on this point? How is a sump/refugium "using up" ammonia any different to a canister? The cycle is the same isn't it? And the plants in the refugium just use nitrates don't they?
And a canister you can clean out, a sump - not so easily.

[Juls]

A sump full of fast growing plants, under high intensity lighting will use the ammonia before the filter has access to it, turning the ammonia into plant growth. Plants do not convert ammonia and release nitrates, instead turning it into a organic carbon that can be removed by hand.

A canister filter simply converts the ammonia to nitrite, then nitrate.

Your left with nitrate.

Plants utilize the ammonia and lock it away, if they have to they will use nitrates but it is not prefered, they will only utilize nitrates if there is no ammonia and sufficient lighting and co2 are available.

The reason planted tanks have little or no nitrates is because the ammonia never has a chance to be converted. As such we dose "nitrogen" from a bottle but this is complex bound nitrogen that includes ammonia, it causes false nitrate readings annoyingly.

A refugium full of fast growing stems under intense lighting would drastically reduce the need to make water changes as a result of nitrate buildup. Although water changes cannot be eliminated in a closed fw system without some kind of trace elements being dosed on a regular basis.

Juls

[Cawdor]

Thanks for the explanation Juls!

[bigjohnnofish]

If your nitrates are getting up to 100ppm, suggest bagging all the fish, 100% water change and reacclimatize the fish like you just bought them.

Juls

everything else you said juls is pretty much spot on.... but i dont agree with taking fish from very high nitrates and bunging them back into a tank with zero nitrates..... from experience a lot of fish will stress and in some cases die....

better soloution is to do 50% wc daily untill you get nitrates down to the desired level.....

and i have tested our tap water many times for nitrates - and have gotten zero each time... it is illegal/offence to leave nitrates in our tap water.....
but i have also tested for ammonia... and get very varied results from 1ppm to as high as 5ppm.... talking to someone in the know up at the mundaring weir... this shouldnt happen - but it does....

a healthy adult fish can go 30 days without food.... so you are much better off under feeding than over feeding.....

[Juls]

I've not been able to find any evidence that going from high to low nitrates is harmful, I believe the sudden change in chemistry from not allowing a sufficent acclimatization is the problem, the nitrate reduction is not the problem.

At a reading of 100ppm nitrates, the fish are slowly being poisoned, at 100ppm nitrates are not the only problem, there is many other toxic compounds that have built up in the water that are also poisoning your fish, the problem is as this happens slowly there immune systems slowly become weaker and weaker as the nitrate increases, eventually the fish will succumb to some form of illness. Also Phermones will have built up significantly by this point leading to considerable stunting in growth of smaller fish in the tank.

One of the problems with making such a drastic change in the water chemistry when nitrates are at 100ppm is that the fish is already "struggling" it's immune system is already compromised so a "sudden" temperature or ph/hardness change is all thats needed to set there immune systems spiraling out of control.

Make no mistake, 100ppm nitrate long term will lead to an early death of your fish, stunted growth, inability to produce consistant healthy fry, inability to properly heal wounds as well as the inability to fight off viruses or disease there immune system would normally be able to fight.

It is easy to think it's not hurting your fish when you see the water at 100ppm and you look at the fish and think "it looks great"

Many fish can live for 10 years or more, how does someone make a assumption that 100ppm is ok based on a day or a week a month or even a year of living in those conditions?

It's a bit like someone buying a gold fish and it dies after 2 years, and the owner thinks, "oh it died from old age" ......

err, sorry but goldfish can live for up to 20 years or more, you poisoned the poor thing to death from not giving it a suitable toxin free home!

Back to the nitrate change, I agree that making massive changes in water chemistry can stress fish to death, but it's important to realise that at high nitrates the fish is already stressed before you make the change, doing huge water changes without removing the fish will probably kill it. It's highly unlikely that the nitrate change is at fault, after all the nitrate is poison, yes they have gotten used to these high levels but they don't somehow suddenly need it to survive! Going from poison to no poison isn't the same as no poison to poison.

For this reason I suggest simply bagging up your fish (properly) and keeping them in a nice temperature controlled dark place, keeping in mind they can easily survive 5 or 6 hours in the bag, (after all they come halfway around the world twice over before they get to your tank in a little bag) Make the changes as neccessary then carefully and slowly reacclimatize the fish, this should not put a "unusual" amount of strain on the fish. Simply leaving the fish in the tank and doing 80-100% water change is far more likely to stress the fish out, than removal and reacclimatization.

This is not really that different from the day they got caught in the wild, then dumped in a holding tank, then back in a bag and shipped to a wholesaler, back in a tank, then back in a bag on a plane, back in a bag, into quarantine, then back in a bag and on a plane then back in a holding tank, then back in a bag and into your car going home then finally back in to a tank. By this point in time having delt with a myriad of different water conditions, probably 4-5 or more bag rides they finally come to rest, only to find 12 months later there new owner is bored, so back in the bag, back to the shop, back in the holding tanks, then back in the bag and in someone elses car and then into there tank...

well to be honest by this point in time it's a utter miracle they are still alive!!

If bagging the fish then acclimatizing it to new water will do more harm than suddenly changing the conditions they are living in, then no fish would make it past the first holding after being wild caught. (or if they are farm raised they wouldn't make it past quarantine).

Going from 0 Nitrates to 100ppm will harm the fish, but if done properly I see no possible reason for harming the fish by going from 100ppm to 0ppm nitrates if the person doing it has his head screwed on properly. It is the other changes in the water that cause the issues if the fish is not given sufficent time to acclimatize.

I believe a 50% water change would inflict more sudden change in chemistry than removal and reacclimatization (only in the case of 100ppm+ nitrates and when done properly), although most larger fish can cope with that level of change, domestic discus in particular seem to be able to cope surprisingly well with 50-70% water changes, although this can be because where they are bred they often get 100% twice daily to eliminate phermones that stunt juvenile growth.

At the end of the day this can all be remedied by keeping a closer eye on your parameters, don't let the nitrates get to 100ppm, you should start making considerable changes if your hitting the 40ppm+ mark, this way you don't get to the point where drastic measures need to take place. Learning the biology and changes of your tank is simply good husbandry, by monitoring your tanks nitrogen cycle and how quickly it changes can allow you to have a good idea when and how often water changes need be. There is no one particular way or quantity in which water needs to be changed, every tank is different, some need to be done 50% every day, others might only need doing once every few months.

you would only need to make a drastic change like removal of fish 100% water change if you let your nitrates reach 100ppm or higher.

in my experience once nitrates reach 100ppm, a 50% water change does not usually reduce the nitrates by 50%, often the next day the nitrates will be back up to 80-100ppm, because of the nitrogenous solids built up in the gravel and filter that caused the high nitrate reading to begin with. It could take quite some time to regain some control with 50% water changes only. By control i mean 10-20ppm reading, that doesn't spiral back out of control in 5-7 days.

All of this is my opinion and experience however, I don't have a problem with other peoples experience, as i know experience and opinion can change over time as you have different experiences. So it's possible one day my opinion on the matter might change based on further experience or knowledge.

Juls

Edited by Juls, 12 April 2011 - 10:01 AM.

[sandgroper]

It's good to have a water change drum constantly ageing water ready for the next water change, i use a 250 liter wheelie bin. This way you can heat, harden and buffer the water the same every time, reducing the chemical imbalance and stress on fish, cheers steve.