Ridiculously High Nitrates

[Hollyweb]

I had some listless fish in my tank the past few days and tonight I found my Dalmatian molly dead along with my golden mystery snail. I decided to go ahead and check my levels and ammonia was 0, nitrites were 0 and pH was fine but when I checked the nitrates, they were ridiculously high, like, around 160ppm. (tested with the API test kit)
 
I did a 50% water change but now I'm a little worried about the rest of my fish. I have some plants that aren't doing so well, and the past few weeks I've been battling algae but I'm just not sure what could be causing my nitrates to spike so suddenly.

 

[Blondielovesfish]

What is your water change schedule? How often and how much?
 
What size is your tank?
 
The dead fish is most likely the cause of the spike.
 
You need to do a bigger water change, 80% minimum. If the nitrate was 160ppm (chances are they're higher) 50% will have only gotten you down to 80ppm which is still too low.

 

[Hollyweb]

It's a 20 gallon and I've been doing about a 30% water change every week and a half to two weeks. I can't do another change right now as I have to get to bed but I will do it first thing when I get home from work tomorrow and see if that helps.

 

[the_lock_man]

Three things that cause high nitrates
 
1) Insufficient water changes. A 30% weekly change sounds reasonable, but this also depends on stock level.
2) Overstocking. Effectively the same is (1), your fish are producing more ammonia->nitrite->nitrate than your water changes are coping with. Without knowing what your stock is, I can't comment.
3) High tapwater nitrate. A spike in nitrate in the tapwater used in your last water change may have contributed.

 

[attibones]

You should be doing around 50% weekly. I do two 50% water changes a week. What is your full stock? I believe the general consensus is that mollies are too large for a twenty gallon anyway.

Go ahead and test your tap water, too. Ideally your nitrates should be no higher than 20-40 ppm above your tap water. If your tap has a high nitrate level, get a product such as Prime by Seachem to neutralize the nitrates enough that it will not affect your tank.

 

[Hollyweb]

They're pretty small mollies.
 
Currently I have 1 male betta, 1 silver molly, 2 sunburst platies, 1 sunburst mickey, 5 whiteclouds, 4 guppies and a clown pleco. I have some Prime I got at the pet store about a week ago that I can put in there but I haven't done it yet because I kind of learned my lesson about medicating the tank before I know what's going on.

 

[CrimsonBoli]

You should be doing around 50% weekly. I do two 50% water changes a week. What is your full stock? I believe the general consensus is that mollies are too large for a twenty gallon anyway.

Go ahead and test your tap water, too. Ideally your nitrates should be no higher than 20-40 ppm above your tap water. If your tap has a high nitrate level, get a product such as Prime by Seachem to neutralize the nitrates enough that it will not affect your tank.

Two 50% changes a week? 100% (not directly) a week? That seems rather high? Is your mains water metered?!

 

[Ch4rlie]

WCMM are not really tropical fish in the sense that they prefer cooler waters, around 18 to 22C (64 to 72F) is preferable.
 
Betta prefer warmer temperatures of around 27C / 80F, and best usually in a tank of their own rather than a community tank with guppies and a clown pleco.
 
Reckon your tank is a bit overstocked to be honest but someone with more knowledge of tank stocking will let you know in better detail than I can.
 
But anyway, sounds like possibly your dead fish has caused a high nitrate spike, as already mentioned, do several water changes to bring nitrate levels back down to an acceptable level (below 40ppm at least)
 
Then test nitrates regularly to see if levels change by a lot or normally.
 
Prime is good water dechlorinator as long as not hugely overdosed, believe up to 5x overdose is safe enough but do calculate dosages accordingly.

 

[N0body Of The Goat]

Three things that cause high nitrates
 
1) Insufficient water changes. A 30% weekly change sounds reasonable, but this also depends on stock level.
2) Overstocking. Effectively the same is (1), your fish are producing more ammonia->nitrite->nitrate than your water changes are coping with. Without knowing what your stock is, I can't comment.
3) High tapwater nitrate. A spike in nitrate in the tapwater used in your last water change may have contributed.

3a) The south coast water comes with ~40-50ppm nitrate as standard, some places up north (in UK) are lucky to have virtually nitrate-free tap water.
4) How much food you feed, number of times per day and its protein content (more protein= more eventual nitrate). Typical young fish bought at stores are in their fastest growing phase and should ideally be fed more than twice per day.
 
Accurate nitrate testing is rarely a precise "science" because the test reagents come out of solution in the bottles, you really have to shake and bang the bottle for a good couple of minutes.
 
While you need to get that nitrate level down to ~30ppm max above how it comes out of the tap, be careful of suddenly changing a lot of the tank water and rapidly reducing the nitrate levels. Similar to "old tank syndrome," it is far safer to do a number of small-moderate water changes through the week eg. 25% everyday.

 

[attibones]

You should be doing around 50% weekly. I do two 50% water changes a week. What is your full stock? I believe the general consensus is that mollies are too large for a twenty gallon anyway.
Go ahead and test your tap water, too. Ideally your nitrates should be no higher than 20-40 ppm above your tap water. If your tap has a high nitrate level, get a product such as Prime by Seachem to neutralize the nitrates enough that it will not affect your tank.

Two 50% changes a week? 100% (not directly) a week? That seems rather high? Is your mains water metered?!

Yeah, my 20 gallon is a tightly stocked sorority tank. I do water changes of that frequency to be sure my water is always pristine. If it was a typical community setting, it would just be the one 50% water change.

 

[Hollyweb]

 

Three things that cause high nitrates
 
1) Insufficient water changes. A 30% weekly change sounds reasonable, but this also depends on stock level.
2) Overstocking. Effectively the same is (1), your fish are producing more ammonia->nitrite->nitrate than your water changes are coping with. Without knowing what your stock is, I can't comment.
3) High tapwater nitrate. A spike in nitrate in the tapwater used in your last water change may have contributed.

3a) The south coast water comes with ~40-50ppm nitrate as standard, some places up north (in UK) are lucky to have virtually nitrate-free tap water.
4) How much food you feed, number of times per day and its protein content (more protein= more eventual nitrate). Typical young fish bought at stores are in their fastest growing phase and should ideally be fed more than twice per day.
 
Accurate nitrate testing is rarely a precise "science" because the test reagents come out of solution in the bottles, you really have to shake and bang the bottle for a good couple of minutes.
 
While you need to get that nitrate level down to ~30ppm max above how it comes out of the tap, be careful of suddenly changing a lot of the tank water and rapidly reducing the nitrate levels. Similar to "old tank syndrome," it is far safer to do a number of small-moderate water changes through the week eg. 25% everyday.
 

 
I live in the US. I've tested ammonia right out of the tap but never tested nitrate or nitrite out of the tap. I did a 50% water change last night and when I get home from work I'll probably do another water change and see how it tests. The only fish in my 20 gallon now that seems to be less active than normal is Brutus, my betta.
 
 
Also, I know that whiteclouds prefer cooler water but I bought them before I knew that. I've had them for several months now and they seem to be doing well with the tropical fish so I've just left them alone.

 

[Hollyweb]

Tap water tested at 0 nitrates. I tested the tank water tonight and it still tested high, probably around 80-100 ppm. I did another 50% change and I'll test again tomorrow. I also added some Prime to the water.

 

[attibones]

Tap water tested at 0 nitrates. I tested the tank water tonight and it still tested high, probably around 80-100 ppm. I did another 50% change and I'll test again tomorrow. I also added some Prime to the water.

Your nitrates were probably off the charts then. When was the last time you had seen the molly alive?

If you were to test the tank now, you should be looking at 40-50 ppm nitrates, which is much better. You certainly want to be under 80. Please post the results for this tomorrow. Should be all sorted by then.

 

[Hollyweb]

I don't remember noticing her, so I'm not sure. She didn't look nibbled on or anything so I don't think she was dead for very long. She wasn't floating though, she was at the bottom. I had a mystery snail that was dead too.