[Ductapemaster]

I had a fish die the other day (my favorite little pleco :icon_frow ) so I immediately tested my water parameters. Ammonia and Nitrite were both 0, but my nitrates were really low, around 5ppm. The tank has been fully established for 5 months or so with no fish deaths and everyone seems pretty happy and healthy to me. When I was cycling the tank, my nitrates were around 20ppm which seemed pretty normal to me.

I just set up pressurized CO2 in the tank and stopped dosing excel last week, and I am still getting things dialed in. The CO2 levels are really low (the indicator is still blue) and I am currently playing with the doses to get the concentration right. I dose a diluted solution of flourish every day (it adds up to the recommended doses per week), but that will change when I get my macro ferts in a couple days.

The tanks pretty well planted with a gravel substrate, two HOBs running. I also do regular water changes (20-30% a week) and vacuum part of the gravel.

Anyone see a reason my nitrates would be so low?

 

[Captivate05]

Your plants are probably taking up more nitrate since you started your co2.

 

[Ductapemaster]

That makes sense. Would that actually be the case after only a week of insufficient CO2 being added though? Either that or would dosing excel cause the same effect?

And regardless of cause, is it anything to be concerned about?

 

[Diana]

Maybe....
Some plants might be able to use CO2 better than Excel.
The constant (24/7) supply of CO2 is probably better than the 'boom then bust' supply of Excel as it is dosed then gets used up.

Anyway, I do not know how this relates to the death of the pleco, if at all.

Low NO3 is not a cause for worry. Just monitor it. As the plants grow better (improving supply of CO2) they will likely start using all the fertilizers in greater amounts. Since you say you have macros on order, I would think the tank will be OK until they arrive.
Temporary solution: Feed a bit more fish food.

 

[Ductapemaster]

Just got my macros last night and I will be starting EI dosing today. Still playing with the CO2 levels...even though I spent a bunch of money on the regulator/valve I can't seem to keep my bps count steady over the long term. I'll keep an eye on the nitrates.

The death of the pleco was just the impetus to check my water parameters, as unfortunate as it was. I miss the little guy.

Thanks for all your help!