Nitrates, live plants and partial water changes

[Robinowitz]

A few weeks ago I started adding live plants to my tanks and am slowly discarding the plastic ones.  I understand that nitrates in the aquarium are good for the plants.  My tanks are cycled and mature.  I’ve always done partial water changes based on nitrate levels being above 10-20ppm on the api master test kit.  So partial water changes happen about once a week.  I’m curious about what level of nitrates (ppm) to leave for the plants before I do water changes? 

[Kurt Brutting]

I keep easy plants and mine seem to do well around 25ppm. I dose easy green and throughout the week I work my way up to 25ppm. For Example for 40 gallons :

After Water Change

Day 1 - 2 pumps

Day 2 - 1 Pump 

Day 3 - 1 Pump 

After that I dose as needed sometimes more sometimes less. 

Every aquarium is different I also use root tabs and fast growing flow plants.

[JoeQ]

My tanks are pretty lightly stocked. My nitrates stick around 10 (sometimes below after waterchange) and things grow well

[Robinowitz]

Thanks.  I started putting live plants in my aquariums about a month ago.  Different varieties of Anubias, Java fern and Najas.  So far they all seem to be ok.  Not decaying and certainly not dying.  Amount of light they need with my lights is still somewhat of a question but I’m letting them tell me.  The level of nitrates were a concern because of the toxicity for the fish.  Based on what you’ve both told me I will carry on with what I’ve been doing until I see a need for change.  I love the dance.  

[Corbidorbidoodle]

I've found that I can have trouble keeping ENOUGH nitrates in the water. Especially when you get a lot of plants in there. They'll grow pretty well at first, then when the naturally occurring nutrients are tapped out, they'll start to stall and get algae-y.

I rarely have to change my water anymore. When I do, it's usually because the driftwood is leaching tannins and I just want to clear the water up a bit. Otherwise I go by the indications on the ACO test strips. They say to change the water after you get up around 100ppm. But my tanks never even get to 50. I've got pretty easy fish though.

My plants are doing pretty well for the most part with the ACO root tabs and ferts.

[Patrick_G]

The old rules for a fish only tank don't necessarily apply with a planted tank since we add Nitrate via fertilizer. In my planted tanks I generally do a water change when Nitrates are above 50ppm and don't seem to be falling. I'll also do a change every couple of months even if parameters look good. I worry about other compounds building up.

[Robinowitz]

Patric_G, your comment about old rules not applying since we add nitrates for plants is an enhancement of my original question.  I am curious to know from those who add nitrate as fertilizer for plants have found to be acceptable levels for their fish only aquariums.  I’m not sure I’ve ever seen a nitrate reading of 50ppm or more in my tanks and if I did would probably consider it an emergency of sorts.  So what are the new rules for nitrate levels in aquariums with fish and since I’ve recently added some red cherry shrimp to a couple of my tanks with fish what are acceptable nitrate levels in them?  It feels like I should know new nitrate levels associated with keeping live plants in an aquarium.  Suppose I’ll start researching… 

[JoeQ]

On 5/17/2022 at 5:47 PM, Robinowitz said:

Patric_G, your comment about old rules not applying since we add nitrates for plants is an enhancement of my original question.  I am curious to know from those who add nitrate as fertilizer for plants have found to be acceptable levels for their fish only aquariums.  I’m not sure I’ve ever seen a nitrate reading of 50ppm or more in my tanks and if I did would probably consider it an emergency of sorts.  So what are the new rules for nitrate levels in aquariums with fish and since I’ve recently added some red cherry shrimp to a couple of my tanks with fish what are acceptable nitrate levels in them?  It feels like I should know new nitrate levels associated with keeping live plants in an aquarium.  Suppose I’ll start researching… 

I don't think youll find a conclusive 'best' nitrate level. For example, i like mine low around 10, Corry says ideally 10-20, other guys like to sky rocket it up to 50. A lot is subjective when it comes to quantities of nutrients, and depends on the tank, on lighting, how many plants, if you have co2 or not and the amount of time you have to put in on upkeep. 

[Patrick_G]

On 5/17/2022 at 2:47 PM, Robinowitz said:

So what are the new rules for nitrate levels in aquariums with fish and since I’ve recently added some red cherry shrimp to a couple of my tanks with fish what are acceptable nitrate levels in them?  It feels like I should know new nitrate levels associated with keeping live plants in an aquarium.  Suppose I’ll start researching… 

When I kept fish only tanks it seemed like the goal was to keep Nitrate levels as close to Zero as possible because they would just keep building up. I’m not sure there’s a rule of thumb for planted tanks, but you'll find your personal comfort point. 

[AndreaW]

My 46G tank had plastic plants that I recently switched out for live plants. My Nitrates usually sat around 40ppm prior to the change. Now that it's planted, I dose EG to make sure the plants have the other nutrients besides Nitrogen, and my Nitrates still seem to sit around 40ppm, but range from 20-80ppm (depending on water changes and adding EG). I'm hoping those numbers drop a little bit over time as the plants grow. For me personally, I would prefer to be between 20-40ppm.