Nitrates Reading At Zero For Several Months Now + Green Water

I’m hoping someone here can help me— I’m new to fish keeping, and I have a 10 gallon tank with 1 guppy in it. I’ve been having two issues (which may or may not be related):


Issue 1. I’ve been getting readings of 0 nitrates (along with 0 ammonia and nitrite) for a few months now, and


Issue 2. I’m having an issue with nearly opaque green water.


Are the 0 nitrate reading and algae bloom in the water related? I thought I had a cycle crash, but it’s now been 4 months of 0 readings now, and there is a fish in there, plus food (I feed him every other day)—wouldn’t the tank start cycling again? Or wouldn’t he be sick if the tank wasn’t cycling at all?


The fish seems to be fine—his fins and scales and tail look great (in fact his tail has gotten bigger and more colorful since I got him in January), and he swims around and eats normally, but I know a cycled tank is supposed to show *some* nitrate, and the green water (which I believe is an algae bloom) just looks nasty. If anyone is able to help I’d appreciate it. Some background info follows.


Background: in December 2018 I started a fishless cycle with a (mostly) new tank using fish food flakes +gravel from an established tank from LFS. My friend who is an experienced fish keeper (but lives 3000 miles away) walked me through it, plus I read a lot from FishLore (I *do* understand the chemical process of the nitrogen cycle). I monitored every day while cycling it, and watched the numbers go up and fall appropriately, and after the readings held at 0/0/5 (ammonia/nitrite/nitrate) for 2 weeks (a total of 5 weeks since starting the cycle) I got 3 guppies in late January. Readings held consistently at 0/0/5 and I was doing 20% water changes every 10 days, but still, by the end of March, only one guppy was left Shortly after the second one died, I noticed my nitrate readings creeping down, until they were 0. My friend suggested I do smaller water changes with less frequency and get a nitrifying bacteria starter, so I did both. I followed the instructions with the bacteria starter, but all 3 readings held at 0/0/0, and the water became whitish-cloudy. I got more gravel from an established tank at an LFS. No change.After a few weeks of white-cloudy water, around late April, the water turned green. Readings stayed 0/0/0. I thought maybe my API test kit was faulty, so I got a new one—still 0/0/0. At this point the water was like pea soup in color.


At the end of June I moved. I kept the filter media and gravel damp, and set up the tank in my new place. Because this was essentially a 100% water change, I had clear water for the first time in 3 months. Within LESS than a week, the pea soup was back, and has stayed that way (photo is from today, tank light is off) Readings are still 0/0/0. What am I doing wrong, and what can I do to address these issues? Also, since the move I no longer live near a LFS, so my options for accessing gravel/talking to someone who knows what they are doing are limited.


Thanks in advance!

 

The algae probably is feeding off the nitrates. How long do you have the light on for?

 

The algae probably is feeding off the nitrates. How long do you have the light on for?

I was leaving it on for around 8 hours a day, but I’ve had it off for the last week.

 

In your post, "green water" was linked. I clicked and was led to this: https://www.fishlore.com/CloudyWater.htm

It pretty much says what I was going to say, so that saves me time. Let me know if you have any questions.

 

In your post, "green water" was linked. I clicked and was led to this: https://www.fishlore.com/CloudyWater.htm

It pretty much says what I was going to say, so that saves me time. Let me know if you have any questions.

Thanks. This is actually an article I had already read (I’ve been lurking on this site since last fall, just joined because the problems described above are getting frustrating). I noticed the article and most about green water say it’s due to high nitrates, but as I said, mine are reading at 0. Could there be any relationship between the 0 nitrate and the algae bloom?

 

The algae is being fed from the nitrates. If you have tons of nutrition and nothing using it, algae is very opportunistic and will appear to take care of that for you.
That's why it's recommended to feed your fish less so that no ammonia=no nitrites=no nitrates, as well as reducing or turning off the light so photosynthesis and whatnot can't happen and allow the algae to grow.

 

you should really consider putting plants in the tank to compete for nutrients
you don't even need to buy aquarium plants, you can just use pretty much any vining plant cuttings (see monstera, pothos, any philodendron)

algae bloom like this is a sure sign of nutrient imbalance... the algae is actually helping you out. this is a beautiful example of nature "taking care of itself"
java moss, java fern, Anubias, banana plant are all pretty good choices for aquatic plants for low maintenance tanks... sometimes hornwort too