Had a "mature tank" episode this week. Nitrate-spike. No indications prior to this that there was a problem -- no algae growth. Regular cleanings and water-changing, but I wasn't testing for nitrites and nitrates regularly.

This has been a stable tank for at least 4 years. Haven't added a fish in 2 years.

One of my fish was acting a little stressed and hiding a lot so I tested the water and found nitrates were off the charts high.

Cleaned the filter, swapped in new filter-media, vacuumed the gravel, changed the water 20%/20%/20% overnight.

Nitrates stayed high.

Added new nitrifying bacteria. Nitrates plummeted to zero. Shock from the drop (probably) killed my prettiest fish.

!&^*%$#%

Stable today. Nitrites and nitrates at zero and remaining fish seem to be active/healthy.

---

I went through something similar in my 90-gallon saltwater tank. Things went sour in less than a day. had me baffled since my bacteria bed was mature and the protein skimmer was working. Like you, I did a 50% water change and added new carbon to the wet/dry reservoir. Eventually, I got everything back in order but lost three fish in the process including an Emperor Angel. I don't want to think what that would mean in today's dollars as fish skyrocketed in cost since I was active.

---

“No persons are more frequently wrong, than those who will not admit they are wrong.” -- François de La Rochefoucauld

"Those who cannot accept the past are condemned to revise it." -- Geo. Mathias

I've never had a fish tank. Is this a urea problem?

Quote
freeradical
I've never had a fish tank. Is this a urea problem?

Nitrates are the end-stage of what began as ammonia in the fish waste. Good bacteria in the filter and around the tank change Ammonia-->Nitrites-->Nitrates. Ammonia hurts fish bad. Nitrites not good, but normally temporary. Nitrates just sort of sit around as the end stage. They aren't supposed to be harmful, unless the concentrations are sky high. You get rid of them with regular water changes.

It's not clear to me what Sarcany did wrong, though, except maybe too many fixes at once? When I fall behind in fish care, I try to right the ship gradually, waiting a day or two between steps.



Edited 1 time(s). Last edit at 11/01/2021 09:41PM by Acer.

Quote
Acer

Quote
freeradical
I've never had a fish tank. Is this a urea problem?

Nitrates are the end-stage of what began as ammonia in the fish waste. Good bacteria in the filter and around the tank change Ammonia-->Nitrites-->Nitrates. Ammonia hurts fish bad. Nitrites not good, but normally temporary. Nitrates just sort of sit around as the end stage. They aren't supposed to be harmful, unless the concentrations are sky high. You get rid of them with regular water changes.

It's not clear to me what Sarcany did wrong, though, except maybe too many fixes at once? When I fall behind in fish care, I try to right the ship gradually, waiting a day or two between steps.

Urea is essentially two ammonia molecules bound together through a carbon atom (specifically two amine groups (—NH2 group) joined by a carbonyl (C=O) functional group). It is a highly functional way for an organism to get rid of nitrogenous wastes. Nitrogenous bacteria then start breaking it down; different species get their energy from each step of the way and since ammonium ion burns the gills of the fish and thus can quickly kill, nitrogenous bacteria are a good thing. Too vigorous of a cleaning will strip the bacteria from it’s substrate, and harm the ecological balance of the tank. Too little cleaning and the nitrogen products build up.

The nitrates are taken up by plants and algae. If the tank is low in nitrates, plants have a hard time growing but the algae problem is practically nonexistent. Since a fish tank is not a complete system (too small for it) it requires intervention to keep it in balance. As noted, though, things can be quasi stable for years and then suddenly go out. When you’ve spent a bit more than you should have on this hobby, and believe me I’ve been there and done that, quick measures can be the difference between losing a few and losing a lot. I once spent thirty bucks on a goldfish (a GOLDFISH!) but he was beautiful and large and what was noted as a chocolate oranda when I got him. I cried when I lost him.

Too big of a change can cause harm, but too small or too slow of a change can cause harm as well. It appears that Sarcany’s ship went bad, as in really bad. Waiting a day or two between steps could be the difference between a small loss or a big one. Props to him for recognizing that the problem was the nitrogen levels and quickly getting it under control. As I’m sure he and others are aware, you can purchase nitrogenous bacteria, either to kick start an aquarium or help maintain it. I’m not normally a proponent of quick multiple changes in an aquarium, but sometimes you just have to.

Diana

Quote
Acer
It's not clear to me what Sarcany did wrong...

I think that I was negligent in letting the water temps cool. I didn't have the heater plugged in over the summer and waited too long to plug it in when the house got cooler.

Cooler temps > fish eating less > waste accumulating (and not getting cleaned up in a quick 20% water-change, needs a thorough vacuuming) > bad bacteria balance and high nitrates.

I didn't catch it early because I had confidence that my mature tank didn't need testing so often and let it go.

---

Are you using a protein skimmer? While it doesn't remove ammonia, it removes the organic compounds that decompose into ammonia then nitrite and nitrate. So it helps keep things in balance. You can buy one or easily make one from PVC (which I did).

here is a simple one (although I would use a longer mixing tube and larger collection cup) -- [www.youtube.com]

---

“No persons are more frequently wrong, than those who will not admit they are wrong.” -- François de La Rochefoucauld

"Those who cannot accept the past are condemned to revise it." -- Geo. Mathias

It's freshwater. I know it's possible to use a protein skimmer with a freshwater aquarium, but they are allegedly not very effective with freshwater and I don't have a lot of spare time to experiment.

...Looks like nitrates are at roughly 5% tonight.

Gonna keep testing once or twice each day for awhile.

---