Nitrate and Phosphate Dosing

[Osler]

I set out to create a nitrate decay curve, a phosphate decay curve, and combined nitrate/phosphate decay curve for my aquarium to better inform me on how I need to dose these "supplements".

Tank conditions on initiation of this experiment are as follows:

SG: 1.023
Temp: 78.8 - 79.0 F
pH: 8.45 - 8.60
Alk: 8.1 dKH
Ca: 483 ppm
Mg: 1480 ppm
NO3: 0 ppm
PO4: 0 ppm

Dosing: Vodka and All For Reef (and I don't want to back off of my vodka dosing)

Given that my tank is low in nitrate and phosphate, my plan was do dose both individually and follow the decay curves and then dose both together to see how these additives modified each others decay curves. This would give me a better idea of how much and how often I needed to dose each additive.

Total system volume is ~210 gallons, with ~150 gallons in the display.

I started with a one-time 50 mL dose of NeoNitro and achieved a nitrate concentration of 4.5 ppm at 1 hour post-dose. This tank concentration maintained for approximately 24 hours and was followed by a relatively linear decline in nitrate concentration in the tank.

By taking the linear portions of the graph, I was able to approximate the daily usage of NO3 in my tank in the absence of phosphate.

My next step was to do the same with NeoPhos. Both the NeoNitro and NeoPhos were recently purchased from BRS.

My initial dose of NeoPhos for the tank was 5 mL based upon recommendations from @Randy Holmes-Farley based upon the information available on the back of the bottle. This did absolutely nothing to my tank's phosphate concentration after 1 hour.

An additional 15 mL dose was done 4.5 hours after the initial 5 mL dose and also resulted in no increase in phosphate after 1 hour. Another 15 mL dose was done at this time and still no increase in phosphate was noted 1 hour later or the next day.

Looking at previous posts on R2R, many have had similar experiences. This has been chocked up to phosphate sequestered in the sand, rock, and biofilm. The prescription has been to dose through and eventually phosphate levels will rise.

However, I began to question the stock solution I was using. Some had posted that when they made their own stock phosphate solution from food-grade products on-line, the expected dose-response was much better than using OTC products.

I ended up making several dilutions of NeoPhos (1 gtt in 17 mL, 2.5 mL in a total volume of 17 mL) and testing these directly. In all cases, the phosphate concentration continued to read 0.00. It wasn't until I tested 17 mL of NeoPhos directly from the bottle that I achieved a reading of 0.08 ppm phosphate. This concentration will in no way allow me to dose phosphate into my tank at a reasonable cost or rate.

Has anyone else tested the stock NeoPhos concentration via dilution or straight from the container?

I find my results to be somewhat disappointing.

I used a combination of Hannah checkers and Red Sea tests to obtain results. I am now out of phosphate reagent for my Hannah checker and awaiting a refill to continue this line of query.

Thanks for reading.

Osler

 

[Reign1]

Well that would make sense as I have been dosing Neo Phos and see little or no change on my phosphae levels.
I only get a low reading when I send an ICP.

 

[Randy Holmes-Farley]

I’ve never tested Neophos, but also see no reason to use it.

 

[Reign1]

I’ve never tested Neophos, but also see no reason to use it.

Been using that and Reefroids. Hopefully my Nitrate is lower now been carbon dosing the last week and want to see some nitrate results.

 

[Randy Holmes-Farley]

Been using that and Reefroids. Hopefully my Nitrate is lower now been carbon dosing the last week and want to see some nitrate results.

What I meant was no reason to use that brand. For dosing phosphate, I recommend food grade sodium phosphate. It is less expensive, can be made to most any concentration for dosing, and carries a purity assurance the hobby product lacks.

 

[Reign1]

What I meant was no reason to use that brand. For dosing phosphate, I recommend food grade sodium phosphate. It is less expensive, can be made to most any concentration for dosing, and carries a purity assurance the hobby product lacks.

Getting there. Starting to follow what Randy is cooking in the kitchen :D Got some Sodium Hydroxide last week.. May mix it up this week as I am really starting to dial in my dosers/Alk usage.

 

[dayttu17]

What I meant was no reason to use that brand. For dosing phosphate, I recommend food grade sodium phosphate. It is less expensive, can be made to most any concentration for dosing, and carries a purity assurance the hobby product lacks.

Hey Randy, where do I find your material. Back in this hobby after over a decade out. Facing new things I never had before.

Considering dosing nitrate and phos so would like to read up on your methods.

Thanks

 

[ColorMeGone]

I use ammonium bicarbonate and sodium phosphate which both can be purchased online. Ebay or Amazon.

 

[Randy Holmes-Farley]

Hey Randy, where do I find your material. Back in this hobby after over a decade out. Facing new things I never had before.

Considering dosing nitrate and phos so would like to read up on your methods.

Thanks

All my articles are in a stick at the top of the chem forum. Many methods are in threads, not articles, and those can be found by searching or asking specific questions and I can help find appropriate threads. :)

This is the ammonia dosing thread:

DIY Ammonia dosing for low nitrate systems

Some reef aquaria have chronic low nitrogen availability. One indicator is very low nitrate. Nitrate dosing is a fine remedy, but it is possible that ammonia dosing may be more beneficial for some organisms since ammonia can be energetically easier to assimilate than is nitrate. For this...

www.reef2reef.com