I have a 75 gallon tank with the following:
-Heater that came with it (bought of craiglist, unsure of brand but I'm thinking tetra) set at 78
-undergravel filter with aquaclear 70 powerhead
-marineland magnum 350 canister with carbon and ammonia neutralizing crystals
-lights, unsure of type, again came with tank
-bubble disc and bubble wall
-lots of decor and a piece of real driftwood
-various amazon swords that seem to be doing okay (new at planted tanks)
-water wisteria (not looking so well. not sure if its just not growing or if my fish are eating it.
-a floating plant
-1 blood parrot
-1 peacock eel
-4 silver dollars
-1 dwarf gourami
-1 juvie black ghost knife
-2 bn plecos
-5 african dwarf frogs
-1 mystery snail
Ammonia 0 ppm
NitrAte 40 ppm
Nitrite 0 ppm
Hope that was enough detail...I usually change 15-20 gallons each week but last week I noticed that spike in nitrate and changed 20 gallons twice. Its back up at 40...
What's causing it and what can I do??