Bobthenurse

In tank #1 three days ago my test showed NH3 0, NO2 0, NO3 20. I did a 30% water change with a gravel vacuum to the front 1/3 of the tank. I have gravel at about 4-5" thick at the back of the tank and 1-3" thick in the front.

Today my numbers were NH3 0, NO2 0, NO3 0. This concerns me. Please, offer any advice on having no nitrates. Is this a good sign or a bad sign? Since I don't have any live plants should I be concerned about a pocket of anaerobic bacteria?

I love this hobby, there is something new to learn every day.

cerianthus

4-5 " is deep gravel. Depending on the size of gravel, may/may not have anaerobic acitivities. Unless deep sand bed (DSB), doubt it. Look from underneath the tank, should see black area on bottom on sand. If new tank vacuumed regularly, very unlikely.

When you vacuum the gravel, do you see bubbles rising from gravel with funky (rotten egg; hydrogen sulfide, smell just like marsh in low tides) odor?

Dont have all the fact as far as age of tank since set up, amt of fish, etc? If small amt of NO3 is produced by tank, may be being utilized by algae or by water changes?

agabr123

i agree with cerianthus, substrate that thick can leave you with pockets of poisonous gas.

since you don't have too many fish in there right now it could just be that they aren't producing that much ammonia. when you did a water change when NO3 was 20, how long had it been before that since you did a water change?

Bobthenurse

Before that it had been 1-1/2 weeks just prior to adding fish and after the tank had cycled. At that time the NO3 was at <20 and prior to the most recent water change it was <20. (which means to me it was, therefore, also >10, but what do I know I'm a fishlore newbie lol.)

I do have a fairly large amount of brown algae that the ottos are working on but one artificial plant has quite a bit of it visible. No other visible algae types at this time. I have read that the brown algae is common with a new tank but would be a bad sign later on?

agabr123

yep, that's correct with the brown algae. it comes often with new tanks. as far as a while down the road, i'm not sure, but now i wouldn't worry about it. the algae is probably part of the reason why it's so low.

i asked about the prior levels because it could just be taking a while for that amount of fish in that sized tank to get the nitrates up that high in the first place, which is why a large WC brought you down to zero. i'd watch it for a week or two and test regularly to make sure your cycle hasn't crashed.