Water readings stay at Zero!?

[Bigbeezy]

I have had my 40gal cichlid tank going for about 5 months. I posted here a few months ago regarding my terribly slow cycle that took 3 months to finish.
It has been a month now since the cycle completed. My ammonia and nitrite levels are always at zero

My question is this:

Is it normal/good that my NITRATE level is constantly at zero? I have only done one 20% water change in the past month, and the level is still zero. Even though the level was zero, I felt it was a good idea to give them a little new water. I thought that in the past few weeks there should have been at least some nitrate accumulation.

I use the API master test kit. The kit is 6 months old, and not expired. I have thoroughly shaken the bottles too. I know the nitrate test is valid because I have had readable nitrate levels in the past during the cycle.

I have a bit of reddish algae on the top of my large slate rock centerpiece that has been there for a few weeks. Could the algae be "eating" the nitrate? This is the only explanation I can come up with. Would it be reasonable for this bit of algae to be capable of consuming the Nitrate?

Any insight would be appreciated. Any comments on how to eliminate the algae would be great too! Thanks everybody!

 

[ashleynicole]

Do you have any live plants?

Even though nitrate levels may be low, it is still a good idea to do a small weekly water change to help remove dissolved organic compounds that accumulate when water evaporates.

 

[Bigbeezy]

No live plants. I plan to do PWCs every couple of weeks for the reasons you said

 

[ashleynicole]

How many fish are in the tank? Maybe they just aren't producing that much waste and the algae is consuming the nitrates?

 

[Sharkbait54]

Did you shake the nitrate bottles as listed?

 

[steez]

Bang the nitrate bottle on the counter, the #2 bottle has a powder in it that settles on the bottom. Gotta make it stir up.

I would definitely stick to WEEKLY water changes, this will keep your ph stable and replenish the minerals/etc in the water that the fish need. Size will depend on nitrates.

 

[bruinsbro1997]

+1.

Lots of people wonder why they get false nitrate readings. If there's not a lot of live plants and it's the API Kit, you simply didn't shake the bottle hard enough. I remember a thread about someone who was getting nitrate readings of 0-5 ppm. When I asked her to shake the bottle for thirty seconds to a minute, they got 40-80 ppm. It's a big difference.

 

[Bigbeezy]

I have 5 cichlids in the tank. They are young, about 2.5-3" long. I do think the bio-load is kinda low like you suggested.

I have done a hardcore shake at least 10x and I have repeatedly banged the bottle on the table numerous times as well. I can say with confidence that I believe my testing kit is sufficiently mixed

 

[bruinsbro1997]

I have 5 cichlids in the tank. They are young, about 2.5-3" long. I do think the bio-load is kinda low like you suggested.

I have done a hardcore shake at least 10x and I have repeatedly banged the bottle on the table numerous times as well. I can say with confidence that I believe my testing kit is sufficiently mixed

Could be. In cycling you dose about 4ppm ammonia, which a fully stocked tank would have. I think it might be taking awhile, depending on what cichlids you have.

 

[jetajockey]

With that amount of time even a few small fish should have built up a significant amount of nitrates. I'd do the 'bang the #2 bottle' trick first and foremost.

Whoops, just saw that you've done that already, lol. Have you used any additives that control nitrates?

 

[Bigbeezy]

There are no additives whatsoever in the tank, aside from the dechlorinator I add with water changes.

My cycle completed about a month ago.

 

[jetajockey]

It's possible that algae could be consuming it (algae utilizes nitrogenous waste just like plants do), but I have no idea at what rate algae does this. One other thing I would do to be certain the api test it working is to test out a source with a known nitrate reading, another cycled tank or even water dosed with KNO3.

 

[Bigbeezy]

I was getting normal nitrate readings up until a few weeks ago. During cycling, I was seeing 10-40ppm. I also had 9 fish then and almost no algae. I "donated" 4 of the cichlids to a LFS 6 weeks ago because I thought the bio-load was too high to cycle. I had been cycling for 3 month at that time, so it was a last resort. I guess that helped because the cycle finished a week after they left the tank. I'm fairly convinced the algae is consuming the nitrate at this point since the nitrate levels have dropped since the algae came in. 5 young cichlids in a 40gal is a pretty light load, right? Thanks for the comments. The fish appear very relaxed so really, I guess I shouldn't be worrying about it. I'm just so used to being paranoid after that hellacious 3 month cycle.

 

[jetajockey]

Yeah, that's not much of a bioload. What kind of cichlids are they? As long as they are healthy and you are testing 0's on ammonia and nitrite I wouldn't worry about it, but I would still up the frequency of water changes to weekly, fresh water is good especially for growing fish.

 

[Bigbeezy]

I will certainly schedule weekly PWCs from here on out. I can tell that they are not stressed anymore cause they have finally started digging holes, a typical cichlid behavior that they didn't previously do. There are 3 Kenyi, a blue Acai, and a red zebra, I believe. Dont quote me tho Thy have roughly doubled in size since I bought them. I love sitting on the couch where they can't see me and watching them. If they see me, they will stop their activities and come to the front of the tank expecting to be fed

 

[jetajockey]

I'm beginning to love africans also. We have some at the store and they are still small but I like watching them, they have their own little territories and have dug pits and set up positions around some PVC elbows I put in the tank for them.

 

[Bigbeezy]

Update:
I took readings tonight before my weekly 25% PWC and they were great!
Ammonia = Zero
Nitrite = Zero
Nitrate = 15-20ppm , after the PWC = 10ppm

Looks like my tank is setting pretty now! Thanks for the help folks!