Water Changes

[steelo]

Hi, I recently stocked a cycled 45 gallon aquarium. Well, today I checked the parameters to make sure everything is in check. Nitrites and ammonia are at 0 and nitrates are around 5 ppm. Do I need to do weekly water changes even if the nitrates are very low? The fish store advised me to keep nitrates under 40. The tank currently has 15 neon tetras, 2 guaramis, a small pleco and 6 rasboras and has only been stocked for a week. Thanks!

 

[eaglesaquarium]

Always.

 

[steelo]

Always.

20%?

 

[eaglesaquarium]

20%-25%

 

[Jordan_Deus]

Hi, I recently stocked a cycled 45 gallon aquarium. Well, today I checked the parameters to make sure everything is in check. Nitrites and ammonia are at 0 and nitrates are around 5 ppm. Do I need to do weekly water changes even if the nitrates are very low? The fish store advised me to keep nitrates under 40. The tank currently has 15 neon tetras, 2 guaramis, a small pleco and 6 rasboras and has only been stocked for a week. Thanks!

Keeping up with water changes isn't only in order to keep nitrates down. Weekly water changes are also important for replenishing minerals in the water, removing/diluting chemicals used by fish for communication, and in order to keep general water parameters stable.

It is best to routinely change large amounts of water weekly for the general health of the fish but also as insurance. In this example I will only take into consideration the Nitrogen Cycle. Let's say this week you skip a water change because your nitrates are only 5 ppm. Next week you over feed your tank a bit, nothing serious, your nitrates jump up to 15 ppm. Towards of the end of the week, for some reason you can't perform a water change. The nitrates will have climbed up even more. Organic matter from weeks prior continues to break down, as well as fish producing ammonia actively. This can lead to accumulation of more and more nitrates, possibly passing 40 ppm (in essence a Nitrate spike) which is bad for the fish. What's even worse is after the nitrates have gone up, you do a large water change to remove all those nitrates, this causes the fish stress as it's environment has suddenly changed.

Always do weekly water changes, the more the merrier. In my opinion 33% is the bare bare minimum per week.

 

[Byron]

I put it much higher; anything less than half the tank is really not achieving much. Depends upon the fish species/numbers and live plants of course, but regardless the more water changed the better. Scientific tests have shown that a once weekly change of 70% is far more beneficial and effective than daily changes of 10-20%.

There is no test to determine when a water change is needed, but the failure to do significant weekly changes will show up in tests. Nitrates should remain constant from week to week; if nitrate is at 10 ppm after the water change, and rises to 20 ppm by the following week, you have a problem. Nitrates, like pH, should remain the same from week to week, and the lower the better. Water changes are intended to create stability in the water chemistry. Once you have the biological system in balance, the water should remain stable and the weekly partial water change ensures this.

Nitrate is only one issue, but as it has been mentioned, it should remain as low as possible, and never above 20 ppm. But in addition to nitrate, and a pH fluctuation, there are substances being added to the water daily by fish that cannot be filtered out by filters or plants (given the stocking most of us have in our tanks), only the water changes. Fish are affected by all of these substances.

 

[steelo]

I put it much higher; anything less than half the tank is really not achieving much. Depends upon the fish species/numbers and live plants of course, but regardless the more water changed the better. Scientific tests have shown that a once weekly change of 70% is far more beneficial and effective than daily changes of 10-20%.

There is no test to determine when a water change is needed, but the failure to do significant weekly changes will show up in tests. Nitrates should remain constant from week to week; if nitrate is at 10 ppm after the water change, and rises to 20 ppm by the following week, you have a problem. Nitrates, like pH, should remain the same from week to week, and the lower the better. Water changes are intended to create stability in the water chemistry. Once you have the biological system in balance, the water should remain stable and the weekly partial water change ensures this.

Nitrate is only one issue, but as it has been mentioned, it should remain as low as possible, and never above 20 ppm. But in addition to nitrate, and a pH fluctuation, there are substances being added to the water daily by fish that cannot be filtered out by filters or plants (given the stocking most of us have in our tanks), only the water changes. Fish are affected by all of these substances.

Thanks, I did not get a chance to change out the water last week but I am going to try to do at least a 25% water change tonight and every week. My only fear is stressing out the fish in the tank, they all seem to be doing great (after losing several neons to mean minor tetras) The water parameters right now are about perfect...so happy I was patient and finished the fishless cycle. I have added a few grass plants, which I cannot remember the name of. However, they seem to be growing pretty rapidly and breaking off forming new plants. I'm hoping this will help keep the nitrates in check or at least slow them down and give the fish a very healthy environment.

 

[Byron]

Thanks, I did not get a chance to change out the water last week but I am going to try to do at least a 25% water change tonight and every week. My only fear is stressing out the fish in the tank, they all seem to be doing great (after losing several neons to mean minor tetras) The water parameters right now are about perfect...so happy I was patient and finished the fishless cycle. I have added a few grass plants, which I cannot remember the name of. However, they seem to be growing pretty rapidly and breaking off forming new plants. I'm hoping this will help keep the nitrates in check or at least slow them down and give the fish a very healthy environment.

Plants help control nitrates but are not going to solve problem nitrates. But you don't have problem nitrates if the nitrate test shows 5 ppm as mentioned in post #1. Regular (every week without fail) partial water changes of at least half the tank volume is necessary to achieve stable water conditions, along with not overstocking or overfeeding obviously.

Plants help because they take up ammonia/ammonium and are faster at doing this than the bacteria, so there is less nitrite (it should always test zero) and thus less nitrate resulting.

 

[steelo]

Plants help control nitrates but are not going to solve problem nitrates. But you don't have problem nitrates if the nitrate test shows 5 ppm as mentioned in post #1. Regular (every week without fail) partial water changes of at least half the tank volume is necessary to achieve stable water conditions, along with not overstocking or overfeeding obviously.

Plants help because they take up ammonia/ammonium and are faster at doing this than the bacteria, so there is less nitrite (it should always test zero) and thus less nitrate resulting.

Thanks, right now I don't believe I'm overstocked for a 45 gallon. I have 12 neons, 6 rasboras, 2 sparkling guaramis, 2 small plants and a tiny pleco. Last night I changed out roughly 10 gallons, which is about 20-25% I'll keep an eye on the nitrates every week and if I notice they keep going up, I'll adjust how much water I change.

 

[Byron]

Last night I changed out roughly 10 gallons, which is about 20-25% I'll keep an eye on the nitrates every week and if I notice they keep going up, I'll adjust how much water I change.

You seem to have missed the point here. Waiting until nitrates go up is waiting too long, the fish are by then being impacted. There are substances in the water than harm fish but for which we cannot measure. Nitrate is only one factor, but there are many other pollutants. A significant regular partial water change is always beneficial regardless of the numbers. At least half the tank volume once each week is minimum. The fish will be healthier, guaranteed, and that should be thee aim of every aquarist.

Waiting until nitrates rise to change any or more water is like smoking cigarettes until you develop cancer and then stopping; the damage has already been done.

 

[steelo]

Okay, good point. I do plan on doing 25% water changes once a week regardless. If I'm finding nitrates are getting too high, I will adjust

 

[Byron]

Okay, good point. I do plan on doing 25% water changes once a week regardless. If I'm finding nitrates are getting too high, I will adjust

Nitrates should remain as low as possible, but aside from nitrates, you seem to be missing the point that unless you are doing larger volume water changes regularly your fish are being negatively impacted.

 

[Joshua1990]

Would a 50% weekly water change be too much? Or should I stay in the 25-30% range?

 

[Byron]

Would a 50% weekly water change be too much? Or should I stay in the 25-30% range?

I change 60-65% of my tanks every week (at one time) and have done for well over a decade. You really cannot change too much water as far as the health of the fish are concerned. And water stability, which is definitely healthier for fish, can only be achieved with significant regular changes.

 

[Joshua1990]

Good deal. I didn't want to stress my fish more than necessary. The tiger barbs don't look good when they get stressed