tank almost crashed.. please advices!!

[giar]

i did my weekly 50% wc this monday 6 march. this afternoon, thursday march 9, i noticed my folks doesnt act like usuall. i tested the water parameter, i got ph 5.5, ammonia (ammonium at low ph) 4ppm, nitrite 0ppm, nitrate 100+ppm.

i did 75% wc right away.

tap water parameter
0.25ppm ammonia
0 nitrite
40 nitrate
ph 7.2 (stabled ph after 12-24hours, right out from tap is 6.2).

tank is definitely cycled, it been running for 6+ months. the parameters normally stays at ph 7.2, ammonia 0, nitrite 0, nitrate 80-100.

i dont think im overstocked.
tank dimension is 8x2.5x2 (285gal).
my folks are
1 HBG aro 35cm
1 albino red oscar 25cm
1 tiger oscar 25cm
3 IT dats 20cm

filters are 2x fx6 + 1 eheim 2260 with total 9 liter seachem matrix. i always use seachem prime while doin wc with phyton.

what the hell might caused this?.. any experienced fish keepers please advices..

 

[giar]

now im really worried if my beneficial bacterias are all compromised.. fak.. the hell did i do wrong during my wc last monday... i did what i always did on my routine wc.

 

[nzafi]

Something got introduced to the tank to screw it up. Either left over food stuck somewhere creating significantly more ammonia, or depending on where you are located you might have gotten "bad" water the last time you did a water change. In the US sometimes cities introduce chemicals in the water to fight something but never tell the population.

 

[Fish Tank Travis]

Did you possibly forget the dechlorinator during the water change? Have you added any new fish recently that have a high bio load?

 

[tlindsey]

I suggest not feeding for a couple of days until parameters stabilize. Check the expiration of your test kit also.

 

[tlindsey]

Its a possibility you got a false reading for ammonia or the water company added more chlorine than usual. Test the water out of your tap.

 

[xraycer]

Perhaps, the city did some sort of maintenance to the water line/supply on Monday(or days before)

 

[giar]

Either left over food stuck somewhere creating significantly more ammonia, .

I'm using tiles as substrate, and I don't see any left over food tho...

Did you possibly forget the dechlorinator during the water change? Have you added any new fish recently that have a high bio load?

I think I did not turn off the filters while filling the tap water in. I am pretty sure I did put the sachem prime before I filled in the tank. could this be the source of the problem?.

I suggest not feeding for a couple of days until parameters stabilize. Check the expiration of your test kit also.

I am using digital PH & Temp kit.. for ammonia nitrite nitrate I'm using API test kit. I don't think they are expired yet. Yeah I will do it. I won't feed the fish for the next 1 - 2 days and see if the water parameters go back as usual.

My tap comes from the well tho, so I don't think it has anything to do with my local water company?.

 

[giar]

do you think my beneficial bacterias were totally compromised?... The ph went under 6, and from my understanding, BB wouldn't survive at PH below 6. =(

 

[xraycer]

do you think my beneficial bacterias were totally compromised?... The ph went under 6, and from my understanding, BB wouldn't survive at PH below 6. =(

If fish are still alive, then your bb should be ok