nitrates sky high

[Dave1993]

so been busy and tank got neglected for a while nitrates are sky high, higher than 75 as thats all my hanna checker goes up to and its blinking 75 its a 90 gallon tank i can do 6 gallon water changes at a time doing 2 6 gallon water changes every day untill nitrates are at 10ppm will this be effective i can't do more than 2 individual 6 gallon water changes a day

 

[TCoach]

Unfortunately, there is no quick fix for this issue, and if you have corals that is a good thing. Do you know what caused your nitrates to rise so high?

2 things you can do, water changes and carbon dosing. I was in your shoes with Nitrates at +50ppm. I now dose vodka and my nitrates are below 10. It will take a while (months), but it will go down. Here is what I read to learn more about this. I just use the least expensive vodka from the store and once I was dosing enough to use my doser, set it on that and made life easy.

HTH,
TCoach

 

[Dave1993]

Unfortunately, there is no quick fix for this issue, and if you have corals that is a good thing. Do you know what caused your nitrates to rise so high?

2 things you can do, water changes and carbon dosing. I was in your shoes with Nitrates at +50ppm. I now dose vodka and my nitrates are below 10. It will take a while (months), but it will go down. Here is what I read to learn more about this. I just use the least expensive vodka from the store and once I was dosing enough to use my doser, set it on that and made life easy.

HTH,
TCoach

i have 1 coral and its not doing so good and i guess this is the cause and it happened cause i neglected the tank been busy so water didnt get changed for like 2-3 months but going to just do water changes this week 12 gallons a day and hopefully that sorts it out

 

[Garf]

i have 1 coral and its not doing so good and i guess this is the cause and it happened cause i neglected the tank been busy so water didnt get changed for like 2-3 months but going to just do water changes this week 12 gallons a day and hopefully that sorts it out

What test kit are you using?

 

[Dave1993]

used API and Hanna

What test kit are you using?

 

[Bucs20fan]

Just trying to get a good idea, have you tested for nitrites? I know those generally dont matter in our reef tank but if there is a presence of nitrites in your water, it will always show sky high nitrates even if that is not the case.

 

[ReefGeezer]

I would take 40 6-gallon water changes to drop your nitrates to 15 ppm even if not more nitrate is added.

 

[Dave1993]

I would take 40 6-gallon water changes to drop your nitrates to 15 ppm even if not more nitrate is added.

how did you work out 40?

 

[Duffer]

samething happen to me a while ago..I used nopox and water changes...with nopox you go slow..you could also dose vodka...keep in mind its a slow process...

it took me over 2 months and my nitrates are down to 15...i have lots of sps and it did not harm them

 

[Dave1993]

how much vodka do i dose

 

[Randy Holmes-Farley Verified Community Expert]

how did you work out 40?

While I'd do fewer larger changes, here's the math (answer above is wrong unless one makes assumptions about accumulating nitrate between water changes):

Each 6 gallon change on 90 gallons water volume (will not be this high in a 90 gallon tank) leaves 84/90 = 93.33% of the nitrate

if you do that 40 times, you leave:

(0.9333)^40 = 6.3% of the nitrate, or 0.063 x 75 = 4.8 ppm

 

[MnFish1]

Here is a calculator - assuming you make 1 ppm nitrate/day and assuming you're starting at 75 (yours could be higher) - and if you make 2 6 gallon changes/day - after 30 water changes (15 days) - you will be at 21.7 ppm. I would get a kit that measures higher nitrates and then use this calculator to figure it out

Effect of Water Changes Calculator

Aquarium calculator; Estimate the effect of repeated water changes on the concentration of a given substance.

www.hamzasreef.com

 

[MnFish1]

While I'd do fewer larger changes, here's the math (answer above is wrong):

Each 6 gallon change on 90 gallons water volume (will not be this high in a 90 gallon tank) leaves 84/90 = 93.33% of the nitrate

if you do that 40 times, you leave:

(0.9333)^40 = 6.3% of the nitrate, or 0.063 x 75 = 4.8 ppm

But - you're not taking into account the daily production of nitrate - or?

 

[Dave1993]

Well 40 water changes it is might start doing 3 a day

 

[ReefGeezer]

how did you work out 40?

I did the calculation if rough numbers. So, you would be doing roughly 6% water changes. When you do the water change, it drops the nitrate concentration by 6%. After each water change, the starting concentration is 6% less, so the net drop is progressively less. Putting that in a spreadsheet showed the answer I gave you. That does not take into account the nitrate your system will generate over the time period it would take to do 40 changes.

Undoubtedly, Randy's calculation is more correct. The take away from both might be that bigger water changes are required to affect nitrate levels.

 

[Randy Holmes-Farley Verified Community Expert]

But - you're not taking into account the daily production of nitrate - or?

Correct, since we have no idea what it is. There may be none at this high nitrate level since higher nitrate may drive more nitrate consumption by denitrification and other processes.

 

[G Santana]

My nitrates went sky high months ago, i started dosing Vodka and it dropped from 70ish to 2.5 as of Monday. It took weeks but this is a great way to keep nitrates in check.
I had to stop dosing because they went so low.

 

[MnFish1]

Well 40 water changes it is might start doing 3 a day

Using the calculator above - if you do 40 water changes you will be at 18. If you do 50 water changes you will be at 16 or so. Again - this assumes your producing 1 ppm nitrate/day (might be high) - also assumes your tank volume is actually 90 gallons (not including rock, etc) and that your nitrate is 75. PS - in you OP you said you could only do 2/day - so if you do 3 - obviously it will be faster. Additionally, if you did 12 gallons at once - as compared to 6 gallons 2x/day - it will also be faster. For example 15 days of 12 gallons (all at once) - will bring your nitrate down to 14.5

 

[MnFish1]

Correct, since we have no idea what it is. There may be none at this high nitrate level since higher nitrate may drive more nitrate consumption by denitrification and other processes.

I was assuming a couple things as well. 1. That the nitrate was probably higher than 75 (as he said) - and 2. as the nitrate 'falls' - more nitrate will be generated. But - I totally agree - that if no nitrate is produced - using the calculator above - doing 12 gallons/day - after 15 days - the nitrate will be 8.8 ppm.

 

[Dave1993]

My nitrates went sky high months ago, i started dosing Vodka and it dropped from 70ish to 2.5 as of Monday. It took weeks but this is a great way to keep nitrates in check.
I had to stop dosing because they went so low.

how much vodka should i dose?