My tank keeps having high nitrates

Hello please can someone help me?
I have 2 danios sick because of the high nitrates. I noticed that the output of the canister filter have a lot of diatoms
Here I list my parameters
volume of the tank: 20 gallons
has been running for 6 months
filter: suusun hw 302 and a under gravel
heater: Yes, in the outline of the filter
water temperature: 78.4
stocking of this tank: 4 danios and 15 cherry shrimps. Before I had 2 small turtles but I had to give them to a friend because they ate 2 danios and all the plants.

Maintenance
I normally change the water once per week (5 gallons)
I use to treat the water the Seachem prime
I vacuum the substrate When I do the water change.

Parameters
I cycled the tank before adding fish
I test the water with strips and api kit

Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 80ppm
pH: 7.6

Feeding
I feed the fish Twice at day just a little bit each time with Glo fish special flake food and top fin pro series tropical fish crumbles and twice at week Frozen blood worms.

I just made a 10 gallons water change and the nitrates drop to 30ppm.
I’m really desperate with this situation, don’t know what to do.

 

I’d cut back your feedings to once per day and increase your weekly water changes to at least 50%.

How often do you clean the canister filter?

 

I’d cut back your feedings to once per day and increase your weekly water changes to at least 50%.

How often do you clean the canister filter?

Ok will do that.
the last time was 2 months ago

 

Have you checked your source water for nitrates? Sometimes they're present in municipal water supplies, so doing a water change might actually INCREASE your numbers rather than decreasing them.

Try testing some tap water and see what you find.

 

Let me check it right now

 

Ok will do that.
the last time was 2 months ago

I‘d also suggest cleaning your canister once every month.

 

Have you checked your source water for nitrates? Sometimes they're present in municipal water supplies, so doing a water change might actually INCREASE your numbers rather than decreasing them.

Try testing some tap water and see what you find.

I checked the tap water: between 0 and 5 ppm

 

I‘d also suggest cleaning your canister once every month.

should I do it today or should I wait?

 

should I do it today or should I wait?

Since it’s been 2 months, I’d say yes.

Be sure to rinse the contents of the filter in water you removed from the tank. Not tap water.

 

Since it’s been 2 months, I’d say yes.

Be sure to rinse the contents of the filter in water you removed from the tank. Not tap water.

Ok I will do it right now.

 

Since it’s been 2 months, I’d say yes.

Be sure to rinse the contents of the filter in water you removed from the tank. Not tap water.

This time the filter was really dirty on the bottom. Is that normal?

 

This time the filter was really dirty on the bottom. Is that normal?

No, that’s why you need to clean it every month! Post your nitrate reading again when you test. I’m curious how much it changed.

 

Ok I will do it right now.

Since it’s been 2 months, I’d say yes.

Be sure to rinse the contents of the filter in water you removed from the tank. Not tap water.

This is the 3rd time I cleaned the filter but this time was the worst. What can be the cause?

 

Maybe you didn’t clean it well the first and/or second time?

 

Maybe you didn’t clean it well the first and/or second time?

Yes I cleaned it well, I changed the sponges each time. Could be because of the turtles that I had?

 

No, that’s why you need to clean it every month! Post your nitrate reading again when you test. I’m curious how much it changed.

Let me check the nitrates now I was waiting to the filter work for a while

 

No, that’s why you need to clean it every month! Post your nitrate reading again when you test. I’m curious how much it changed.

Drop to 20ppm. Can I do other water change today or should I wait until tomorrow?

 

Yes I cleaned it well, I changed the sponges each time. Could be because of the turtles that I had?

Yikes! By changing sponges you risk crashing your cycle. Whenever possible, try to just rinse them out in old tank water to preserve your beneficial bacteria colonies.

Also, yes. Turtles are filthy.

 

Drop to 20ppm. Can I do other water change today or should I wait until tomorrow?

Being that you’ve got nitrates down to 20 ppm, I’d give your fish and tank a break until tomorrow. You don’t want to change your water parameters too dramatically too quickly.

As stated above, rinse your filter media in tank water. Don’t throw them away unless they’ve literally fallen apart.

 

Yikes! By changing sponges you risk crashing your cycle. Whenever possible, try to just rinse them out in old tank water to preserve your beneficial bacteria colonies.

Also, yes. Turtles are filthy.

I changed the white one and left the blue and the green. I shouldn’t change that sponge then? I have other media for the bacteria colonies I changed them because I thought that the sponges where to filter the dirt, I didn’t knew that.
thanks so much

 

I changed the white one and left the blue and the green. I shouldn’t change that sponge then? I have other media for the bacteria colonies I changed them because I thought that the sponges where to filter the dirt, I didn’t knew that.
thanks so much

Don’t change any filter media, including sponges.

Some manufacturers will tell you to change them out periodically, but that’s only for the benefit of their sales quota.

 

Being that you’ve got nitrates down to 20 ppm, I’d give your fish and tank a break until tomorrow. You don’t want to change your water parameters too dramatically too quickly.

As stated above, rinse your filter media in tank water. Don’t throw them away unless they’ve literally fallen apart.

I rinsed the media and the 2 remaining sponges on the tank water and throw the white one because I didn’t knew. Next time I won’t change it.
Thank you so much I really appreciate it

 

Looks like you found your high nitrates. That sludge was serious. Agree with all 50% weekly water change and clean the canister once a month. Rinse all sponges in old tank water and replace. I wouldn't do anything for a week personally let it all settle down and next week I will be in track

 

Looks like you found your high nitrates. That sludge was serious. Agree with all 50% weekly water change and clean the canister once a month. Rinse all sponges in old tank water and replace. I wouldn't do anything for a week personally let it all settle down and next week I will be in track

Now I was thinking on the under gravel filter , what should I do with it?. I keep thinking all was because of the turtles because I had 6 danios, now I only have 3 and 15 cherry shrimp one of them is carried with egg. They couldn’t make all that dirt. Hope it gets better since the turtles are gone and I cleaned the filter.
thanks so much, I will keep updating this thread.

 

Don’t change any filter media, including sponges.

Some manufacturers will tell you to change them out periodically, but that’s only for the benefit of their sales quota.

Definitely I will do that!

 

Make sure you're not overfeeding. I had a bad habit of liking to "power feed" my fish (multiple large meals daily) so they could grow to a monstrous size but ended up with uneaten food on the substrate. I never bothered cleaning it up because I figured my Pleco would vacuum for me; even the Pleco had trouble eating all the pellets + shrimp + worms + chopped up fish, etc. Because of my laziness I didn't pick them out.

My maintenance was weekly 90% water changes with gravel vacuum and filter disassembly and cleaning (media too). About 5 days later I test my water and it's 180PPM! Even after all that ^

So yeah, I concluded uneaten food and/or frequent feeding may contribute to very high nitrates. Bioload of livestock may influence as well. I'm sure you don't "power feed", but just be cautious to not overfeed.

 

Make sure you're not overfeeding. I had a bad habit of liking to "power feed" my fish (multiple large meals daily) so they could grow to a monstrous size but ended up with uneaten food on the substrate. I never bothered cleaning it up because I figured my Pleco would vacuum for me; even the Pleco had trouble eating all the pellets + shrimp + worms + chopped up fish, etc. Because of my laziness I didn't pick them out.

My maintenance was weekly 90% water changes with gravel vacuum and filter disassembly and cleaning (media too). About 5 days later I test my water and it's 180PPM! Even after all that ^

So yeah, I concluded uneaten food and/or frequent feeding may contribute to very high nitrates. Bioload of livestock may influence as well. I'm sure you don't "power feed", but just be cautious to not overfeed.

Thanks for the advice I will keep an eye on it. Normally the shrimp ate the leftover food but I will feed them just once per day.

 

I was looking on internet why do my filter had so much diatoms and look what I found :

Silicates
Having excess silicates in the tank is just way too tempting for diatoms.
When you add new sand substrate, especially play, blasting or pool sand, it creates a huge spike in silicates. Eventually, the diatoms should eat up the silicate and then die off, but this could take months.

Some salt mixes for marine tanks contain silicates. Check the label and consider changing brands if your salt mix contains silica.

High Nitrates
Nitrates are a natural byproduct of the nitrogen cycle. As fish waste breaks down, it puts off ammonia (NH3 ).

The beneficial bacteria in your filters and substrate process the ammonia and create nitrite (NO2 -1). Then the nitrite gets turned into nitrate.

Over time, nitrate can start to build up in your water if it’s not removed by water changes.

Now all make sense because the last time I cleaned the filter I changed the substrate from fluorite to sand plus the high nitrates from the dirt of the turtles.

 

I was looking on internet why do my filter had so much diatoms and look what I found :

Now all make sense because the last time I cleaned the filter I changed the substrate from fluorite to sand plus the high nitrates from the dirt of the turtles.

Could be, but diatoms are also very common in newly set up tanks. They’ll eventually go away on their own. Nerite snails also help.

 

Thank you

 

Hello guys I been doing a 25% water change and substrate cleaning every other day because nitrates are 10 ppm but today I did a 50% water change because ammonia was 0.25. Do you guys think this is normal? Should I take out the under gravel filter? Should I wait? I don’t know what to do.

 

YEs I would also add that turtles do create a lot of waste so i am not surprised you had that much filth in the filer. I had turtles for 10 years and believe me when i had HOB filters i would be cleaning them monthly or every 3 weeks because the filter would actually clog up cause of all the filth they produce. Also you should never put turtles with any fish unless you want the turtles to eat them. Turtles will literally eat anything they can catch believe me i know. I have 2 of my turtles in a 150 and I threw in some minnows and goldfish about 60 in total and after 1 month only 7 minnows and 1 goldfish survived the onslaught.

 

If your sponge media is your mechanical media you should clean it aggressively. I take mine outside and blast it with the garden hose. It's not good to keep decomposing waste in your tank or filter.

 

YEs I would also add that turtles do create a lot of waste so i am not surprised you had that much filth in the filer. I had turtles for 10 years and believe me when i had HOB filters i would be cleaning them monthly or every 3 weeks because the filter would actually clog up cause of all the filth they produce. Also you should never put turtles with any fish unless you want the turtles to eat them. Turtles will literally eat anything they can catch believe me i know. I have 2 of my turtles in a 150 and I threw in some minnows and goldfish about 60 in total and after 1 month only 7 minnows and 1 goldfish survived the onslaught.

Thanks so much! I gave the turtles to a friend.

 

If your sponge media is your mechanical media you should clean it aggressively. I take mine outside and blast it with the garden hose. It's not good to keep decomposing waste in your tank or filter.

I cleaned well the filter a week ago. I’m thinking that could be the under gravel filter. I did a 50% water change yesterday and look at the lectures today
The ph is 7.6
Ammonia 0.25 ppm
Nitrite 0 ppm
Nitrate somewhere between 5 and 10ppm
I’m really concerned

 

If your sponge media is your mechanical media you should clean it aggressively. I take mine outside and blast it with the garden hose. It's not good to keep decomposing waste in your tank or filter.

I changed the white sponge and cleaned in the water tank throughly the green and the blue ones. And rinsed the biohome media too.

 

I changed the white sponge and cleaned in the water tank throughly the green and the blue ones. And rinsed the biohome media too.

Did you say you washed your bio media with tap water or hose??? you never want to replace or clean your bio media with regular water. You should always clean it with your tank water because you will end up getting rid of your beneficial bacteria. IF* you did clean the bio media with regular water you have just destroyed your beneficial bacteria and are basically starting the nitrogen cycle all over again.

 

Did you say you washed your bio media with tap water or hose??? you never want to replace or clean your bio media with regular water. You should always clean it with your tank water because you will end up getting rid of your beneficial bacteria. IF* you did clean the bio media with regular water you have just destroyed your beneficial bacteria and are basically starting the nitrogen cycle all over again.

No, i took a bucket from the aquarium and there I rinsed all the media there.

 

No, i took a bucket from the aquarium and there I rinsed all the media there.

ok perfect. did you say you still have high ammonia and nitrites?

 

ok perfect. did you say you still have high ammonia and nitrites?

Well nitrates don’t go down they still at 0.10 ppm
And ammonia was 0 ppm 2 day ago but now is 0.25 I did a 50% water change and just gave food 1 time at day to the fish (minimum). I think can be the under gravel filter but I’m new to all this so maybe I’m wrong. But this tank have me cleaning every day