Help! High Nitrates/new To Freshwater Tanks

Hello fish-knowledgeable folks!

I am in desperate need of help with my freshwater tank. We are currently having a problem with super high nitrates and despite trying several ‘fixes’ I read about on google, I can’t seem to bring the levels down.

Stats on our tank:
36g bow front
2 gourami’s
5 tiger barbs
1 rainbow shark
1 pleco
We have a Sun sun 405(?) canister filter and an Aqueon 50 HOB filter, an air stone that runs 24/7 and heater preset to 78*.

The tank was started about a year and a half ago. We began with planting a few different types of plants, cycled it for 2 months, then added fish. We started with the 2 gourami’s, 6 tiger barbs, 1 rainbow shark, and 2 mollies. Both mollies have since passed on and 1 of the tiger barbs mysteriously disappeared one day. This was within the first few months of having the fish. We’ve been doing about 15% water changes weekly but never really tested the water (my husband was incharge of the tank maintenance). Everything seemed to be going well up until about 4 weeks ago.

We first noticed that our plants never really thrived and we have a significant amount of algae growth. Did some research and decided to get a better lighting system. Husband also came home with a pleco who does a fantastic job on the algae situation. Since then, we’ve noticed the plants ‘greening up’ and can see new growth beginning to happen. Fish always seemed healthy/active; no concerns until 2 weeks ago.

I randomly decided to test the water one day. Water came back with pH 8.0, no nitrites, ammonia at 0.25ppm, and nitrates at 160ppm. And I panicked. Side note: I am the guilty party for over feeding the fish- they’re fat. I have learned my lesson.

We cleaned out the canister filter- replaced the filter media with a new magnum bonded pad filter, deep blue professional nitrate reducer filter media pad, and a deep blue professional advanced poly fiber filter media pad. All new media was rinsed with tank water. We reused all of the original bio media which was kept in the canister water during the cleaning. We also changed the filter media on the Aqueon HOB as it was due for replacement. We performed our weekly 15% water change as well. Fish seemed happy, tolerated the ‘overhaul’ just fine.

Following week, retested the water. pH now 7.6, no nitrites, ammonia persisting at 0.25ppm and nitrates down to 80ppm. Did another 15% water change. At this time I started to noticed that one of our gourami’s color wasn’t as vibrant as it was before. Activity still the same and still readily eating. Attributed it the new lighting system fading her color.

This week, retested the water: pH 7.4, no nitrites, ammonia continues to register at 0.25ppm, nitrates back up to 160ppm. This week our faded gourami appears even more faded in color and is now bloated. Still active but not eating as readily as before. Other gourami appears fine. 3 of our 5 tiger barbs are now also hanging out behind the HOB filter- which is very unusual for them. The other 2 tigers are acting normal. Rainbow shark has become more active with the night setting on the new lighting system, but otherwise appears healthy. The pleco has tripled in size, also appears healthy.

What is the best way to bring down the nitrate level in my tank? We’ve been using tap water for the water changes (our tap water has nitrates at 5ppm) and a water conditioner. Why are my barbs suddenly acting weird and is my gourami going to die? I’ve reduced the feedings to once every 2 days at this point (they’re all still fat). Will R O water help bring down the nitrates? I’m at a loss here and am completely attached to my fish... I don’t want to lose anyone while we try to fix the water situation.

Advice? Help? Please..

 

Welcome to fishlore!

I think the main problem is that 15% water changes are not enough, especially with the heavy stocking you have.

For example say you had a tank with 80ppm nitrates and your tap water had no nitrates. If you did a 50% water change then in theory the tank would have 40ppm nitrates. If you did a 75% water change the tank would have 20ppm nitrates.

The fish have probably got used to the very high nitrates even though they are bad for them. I would recommend slowly lowering the nitrates by doing 25% water changes every other day until the nitrates are at 5-10ppm. Once they are at a safe level I would do 50% water changes twice a week.

What test kit are you using?

 

The only real "fix" that I have found that works for nitrates is water changes. You need to do much larger water changes going forward.

 

Thank you so much for your help!

I am using the API freshwater master test kit to test the water.

We can definitely start the 25% water change every other day. Should we try using RO water, or is our tap water sufficent?

Any ideas on the strange behavior of the barbs or the sick gourami?

Welcome to fishlore!

I think the main problem is that 15% water changes are not enough, especially with the heavy stocking you have.

For example say you had a tank with 80ppm nitrates and your tap water had no nitrates. If you did a 50% water change then in theory the tank would have 40ppm nitrates. If you did a 75% water change the tank would have 20ppm nitrates.

The fish have probably got used to the very high nitrates even though they are bad for them. I would recommend slowly lowering the nitrates by doing 25% water changes every other day until the nitrates are at 5-10ppm. Once they are at a safe level I would do 50% water changes twice a week.

What test kit are you using?

 

I would use your regular tap. Once you have your nitrates under control, you can always test after a week and see where your nitrates are. That way you can tell how much you may need to change. On my goldfish tank (46 gallon, 3 fancies), I routinely change around 60-70 percent each week.

 

If they are bloated I would start simply first......blanch and deshell a couple of peas and throw them in. Peas can help them poop and clear them out. Did you quarantine the pleco before adding him to the tank? How soon after getting him did this start?
When you replaced and cleaned your filter media you likely wiped out a portion of your bacteria colony. This is why you are seeing ammonia.
If this all started within a few weeks of bringing in the pleco you may have introduced a parasite or illness into the tank with him.

 

30% water changes twice weekly.
That's the best prescription...IMO

 

Thank you so much for your help!

The ammonia level has been 0.25ppm since before we cleaned the canister filter and replaced the media. It has yet to change...

No, the pleco was not quarantined prior to adding him into the tank (I had no say in this, I didn’t want to add anything else to the tank since we have a precarious higharchy established already between our tigers and the shark. But lo and behold, I came home from work one night and Ta-da! pleco in the tank). He was also purchased from Petsmart while all
of our other fish are from a tropical store. My gourami started to appear faded with a week or two of the pleco addition, the bloat was first noticed in the past few days. The tiger’s strange behavior had just started with the past few days as well. Everyone else seems normal so far. How would do you suggest treating for a parasite or illness?

I can definitely try the peas! I’ll try most anything at this point...

If they are bloated I would start simply first......blanch and deshell a couple of peas and throw them in. Peas can help them poop and clear them out. Did you quarantine the pleco before adding him to the tank? How soon after getting him did this start?
When you replaced and cleaned your filter media you likely wiped out a portion of your bacteria colony. This is why you are seeing ammonia.
If this all started within a few weeks of bringing in the pleco you may have introduced a parasite or illness into the tank with him.

 

Thank you so much for your help!

I am using the API freshwater master test kit to test the water.

We can definitely start the 25% water change every other day. Should we try using RO water, or is our tap water sufficent?

Any ideas on the strange behavior of the barbs or the sick gourami?

Tap water is best. RO water is too soft and you have to add stuff to make it suitable for fish. Your tap water only has 5ppm nitrates and should be fine.

 

I would try the peas.....then watch their poop. See if it looks white or off in any way. I really don't like messing around with meds. But when I do I usually start with General Cure.
I know some people also try aquarium salt, but I have corys, nerites, and plants. So salt is not an option for me. You could try pulling the affected fish out and putting them in a bowl with tank water and the right amount of aquarium salt. Leave for 15 mins or so and then put them back in the tank.