Cause of Nitrate Spike

[Penjet]

AQUARIUM INFO

• 30G / sliding glass top
• 2x 30G hob filters on each diagonal side of aquarium
• 50% water change every 2 weeks
• 2 small "bubble walls (3-4 inches long) along the back of aquarium
• Led lightstrip above aquarium (runs 8-12 hrs a day)
• 1 java fern in center of tank, with large stones to anchor (no stones on bottom otherwise

Water conditions

• nitrite: 0 ppm
• pH: 7.8 – 8.0
• nitrate: 20ppm
• ammonia: 0 ≤ 0.1

Aquarium was established 3 years ago. It was populated by a fancy Fantail ( a bit over 3 yrs) and a Black Moor (a little over 2 yrs)--both pet store purchases.

I feel sometimes like I know less than I think!

QUESTION 1
What can cause a Nitrate Spike of 0 up to 20ppm (maybe 25) in a two week period? Tank has been fine for months if not years. The moor suddenly dies (had been seeming lethargic, but nothing ongoing) one morning, and I dragged out the test kit to see that the Nitrates had jumped since last test (about 2 weeks).

QUESTION 2
The Fan-tail has been swimming upside down for over a year (have been feeding him peas, broccoli and occasional "bath" in a light epsom water solution in cup). Someone had told me it was likely swim bladder/constipation...but than someone else had said the breed (squatty) is prone to digestive issues, and this may 'just be.'

Fan-tail is alive however, and Moor (plucky and apparently healthy until recently) is dead.

Any insights?

 

[54seaweed]

first thought would be over feeding

 

[PassengerTN]

20ppm is good. It isn't harmful at all. You actually should be more concerned about having zero nitrates than 20 unless your tank is very heavily planted.

Jesse

 

[Penjet]

followup

Thanks.

The fish were fed a skinned pea (1-2 peas each) in the evenings.
In the mornings they got algae wafers, broccolli (just the fleur part, small amount) and more often sinking food.

The NO(2) is pretty much zero.
The NO (3) is again (after 50% change weekly) 20ppm.

I am confounded. One HOB uses a filter pack, the other is the old standby Fluvia with the well-used sponge , filter floss in bottom, and the beads in the top.

How can it change so rapidly after so many successful years?

 

[PassengerTN]

If your nitrate stays at zero, your tank isn't cycled. Also likely show positive amounts of ammonia and/or nitrite. No nitrate = no completed nitrogen cycled = bad. You're fine. 20ppm is 100% acceptable and is not an issue in the slightest.


Jesse

 

[Penjet]

Thanks Jesse. Just trying to wrap my head around why.

Not cycling (and maybe I don't understand it correctly)...How can that happen after several years of successful tank tho? I thought I had established it when we started (with the water additive and food, and the wastewater from the first tank and gravel a few years back). everything settled out over time with the test kit (nitrites dropped, etc.)

Could it be algae wafers? The fern growing? Someone screw up a water change.

 

[brennae]

Have you tested your tap water lately? Maybe something in your water changed? Are you on municipal water or a well?

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