Carbon source for effective phosphate reduction

[djkms]

Hello all,

I am on a quest to find an effective carbon source for phosphate reduction.

So far the tried and true phosphate reduction methods are:

GFO - highly effective but its basically taking a hammer to the situation and the drawbacks are potentially bottoming out the phosphate and surprisingly what else is pulled from the water column with this method. Oceamo actually ran a test of what else is stripped from the water column and their findings are found here.
This is the method I currently use and what I want to get away from. I am able to manage almost a perfectly steady reading test to test weekly by running my GFO reactor on a timer through my Apex which runs the reactor for 10 minutes on and 5 minutes off throughout the day. The biggest issue for me personally is I run the Captiv8 method (much like moonshiners) and I am basically throwing away money with the GFO stripping away minor and trace elements along with phosphate.

Lanthanum Chloride - Super effective at targeting phosphate but potentially lethal to fish. I have used this method as well with great success. I am super cautious with this though. I drip it into my overflow box very slowly throughout the day into 5 micron socks. I have observed no ill effects with my fish but the horror stories are out there. I also notice increased levels of lanthanum on my ICP tests and the continued use of this method and the resulting buildup on lanthanum are unknown at this point (as far as I can tell with the research I have done).

Macro algae's - refugium, turf scrubbers, etc. I don't have much experience with this to be honest. Are the effects towards phosphate reduction more skewed towards nitrate reduction much like vodka, vinegar?

Vodka/Vinegar - great at reducing nitrate. I do not find it effective at all reducing phosphate


I know some may come in and say, feed less. Not really an option for me as fish health is of the utmost importance for me and I feed multiple times a day, mainly due to over a dozen anthias in my system.

So this leads me to the next phase of my journey and I am looking into an effective carbon source for reduction that does a good job specifically targeting phosphate with minimal impact towards other elements. I do want to make sure I am safe about it though and not introduce a product/chemical/compound/element that can/will cause harm immediately or over time.

What has intrigued me are a couple things - Tropic Marin Elimi-NP and Bacto-Balance. The problem with Bacto-Balance was the fact that I ran it at their max recommended dose and my phosphate still crept up. I can lower it with Elimi-NP but with a 600 gallon tank it will just be more expensive for me then I want to pay to run this product full time. It is however effective in reducing phosphate. So the question is, what in it? They list the ingredient as Polyalcohols. What is that exactly? Well Randy answers the question as basically no idea really. The term is too broad. of course if TM listed the ingredients most reefers are the DIY type and that would cut into their profits so I do understand not listing what it is. That being said, I believe TM has talked about long chain polymers in some threads here on R2R which gives us a little more insight to what we can use for the DIY crowd.

I did find an interesting thread here by @LeadHead83 which didn't seem to pick up much steam. for me personally I am interested in the Propylene Glycol in his recipe. Could this be the main or one of the main ingredients in TM's product? The effectiveness of PG has a phosphate remover is mentioned here.

Another reason that has me leaning in towards PG dosing is my recent use of Prazipro. The main ingredient in Prazipro is dipropylene glycol which is a carbon source. Running this treatment decimated my nutrients which are discussed here with Jay in the fish treatment forum. I don't know the exact difference from dipropylene glycol from Propylene Glycol but they both appear to be carbon sources.

Fact is I can buy a gallon of Propylene Glycol from Amazon for about $30. Elimi-NP is $18 for 250ml. If PG effectively does the same thing, why not explore this option.

If I decide to experiment with PG I will post my findings here.

Your thoughts and experiences appreciated!

Kris

 

[Randy Holmes-Farley]

My expectation is that switching between organic types is not going to make a big difference in the amount of phosphate consumed per nitrate consumed.

 

[Stevorino]

In my experience, nothing beats LC for phosphates reduction, especially when dosing over time into adequate filtration.

I've been using it in some form for almost a decade and never experienced problems with fish, even when being relatively cavalier about it's application.

I do wonder how many of the LC horror stories are misdiagnoses or downstream issues, simply because it can be so difficult to pinpoint problem sources in this hobby.

The accumulation of Lanthanum is an interesting concern. I'd love to hear what @Randy Holmes-Farley thinks of that and if there's a solution other than regular water changes to keep it at bay.

 

[djkms]

My expectation is that switching between organic types is not going to make a big difference in the amount of phosphate consumed per nitrate consumed.

Thanks for the reply, Randy. Any thoughts on why I am able to reduce phosphate with Elimi-NP and not with Vinegar? Is it just simply I am not dosing enough vinegar to reduce phosphate where elimi-np is a much more concentrated carbon source?

I know you have answered it before but any newfound thoughts or issues dosing Propylene Glycol?

 

[Randy Holmes-Farley]

Thanks for the reply, Randy. Any thoughts on why I am able to reduce phosphate with Elimi-NP and not with Vinegar? Is it just simply I am not dosing enough vinegar to reduce phosphate where elimi-np is a much more concentrated carbon source?

I know you have answered it before but any newfound thoughts or issues dosing Propylene Glycol?

Not knowing what elimi NP is or its concentration, I cannot say whether it is a chemical or concentration effect, or something else.

Propylene glycol is probably Ok to use, but I'd give it a slow ramp up since it may be used by fewer species.

 

[rishma]

I am not sure if different types of carbon dosing can really target phosphate, I’ve never seen a good explanation for that claim.

HOWEVER…

I am able to manipulate up/down and stabilize my phosphate by adjusting my dose of NP Bacto Balance. It is carbon dosing but also has nitrogen and phosphorus. I don’t know exactly what it is, which is usually a no-go for me, but it works very well and is inexpensive.

Also, many of us have seen that the use of ammonium bicarbonate results in phosphate reduction. Those that have tried it tend of to have low nitrate systems, so I cannot say it applies in all cases. I suspect the affect might be more pronounced while carbon dosing.

 

[djkms]

580 gallon total system volume

Propylene Glycol dosing day 1
5ml PG per day
NO3 8.3
PO4 .14ppm (47ppb Hanna ULR Phosphorous)

Other reduction methods currently online - Vinegar dosing 150ml per day (break even is 250). 100 micron Filter socks clogging almost daily with the vinegar dosing and white film on the glass and cleaning every 2 days but noticeable at the end of the first day.
GFO - 4 Cups in a reactor 10minutes on, 5 minutes off all day

I will test again on Wednesday and reduce Vinegar and GFO once a reduction is noticed. I plan on testing Wednesday and Saturday mornings.

Obviously we won't know how effective this is on NO3 and PO4 until vinegar and GFO are offline which I hope to do in about a week or so.

 

[djkms]

Propylene Glycol dosing day 3
5ml PG per day
NO3 6.7
PO4 .12 (38ppb phosphorous)

Reduced Vinegar to 50ml per day from 150ml
GFO - 14 minutes off 1 minute on to keep it tumbled periodically to prevent clumping until I can take the reactor offline

Dosing ammonium bicarbonate = 250ml per day to increase NO3 by 1ppm
Note from Randy's Ammonia dosing thread: "0.1 ppm ammonia (equivalent to 0.36 ppm nitrate"

Will test again on Saturday

 

[djkms]

03/15/2025 - 5ml PG per day
NO3 8ppm
PO4 .16 (51ppb phosphorous)

• Reduced ammonia dosing by 1/2 to 125ml = .5ppm NO3 daily
• GFO reduced again to 59min off 1 min on (still need to take it offline)
• increased PG to 8ml per day

03/18/2025 - 8ml PG per day
NO3 7.6
PO4 .12 (39ppb phosphorous)

• reduced PG to 7ml per day (should be my break even, roughly)

 

[rishma]

03/15/2025 - 5ml PG per day
NO3 8ppm
PO4 .16 (51ppb phosphorous)

• Reduced ammonia dosing by 1/2 to 125ml = .5ppm NO3 daily
• GFO reduced again to 59min off 1 min on (still need to take it offline)
• increased PG to 8ml per day

03/18/2025 - 8ml PG per day
NO3 7.6
PO4 .12 (39ppb phosphorous)

• reduced PG to 7ml per day (should be my break even, roughly)

Appreciate you sharing the progress. How will you consider if the PG or the ammonia is driving the PO4 reduction/control?

 

[djkms]

Appreciate you sharing the progress. How will you consider if the PG or the ammonia is driving the PO4 reduction/control?

I am sure it is a combination of both. At some point once i get this regimen stable for a month I could stop ammonia dosing for a week or 2 and test every couple/few days and see how that affects phosphate.

I do have to dose ammonia though because, as to Randy's point, this is dropping NO3 at a much higher rate then PO4. That being said it is obviously dropping PO4 as well which I was never able to accomplish with vinegar alone and TM products are not cost effective for me with a 600 gallon tank.

At the end of the day though, I am not trying to run a controlled test to find out exact consumption rates of PG and/or ammonium bicarbonate between NO3 and PO4. I am just trying to find a carbon source that shows to be effective at removing phosphate, regardless of the nitrate consumption. I was dosing 250ml vinegar daily and no reduction in phosphate. My filter socks would clog almost daily. Now I am dosing 8ml of PG, last filter sock change was 5 days ago and see a phosphate reduction which I never saw with vinegar. How much of it is the ammonia bicarb dosing? Hard to say for sure but I would bet its skewed toward the PG for sure. What I can say is 8ml of PG is more effective then 250ml of vinegar at reducing NO3/PO4 in my system.

I am just trying to take it slow as I have a lot of livestock in my 600 and don't want to experiment too fast too much with my baby ;)

 

[JayM]

Can I ask why you're trying to lower PO4? It's just about dead center of where Randy suggests a reasonable high and low range should be.

 

[djkms]

Can I ask why you're trying to lower PO4? It's just about dead center of where Randy suggests a reasonable high and low range should be.

At this point I am not trying to lower it, trying to maintain it now around .1

If I do nothing - no carbon source, no GFO, no lanthanum PO4 will rise in my system.

 

[topjimmy]

In my experience, nothing beats LC for phosphates reduction, especially when dosing over time into adequate filtration.

I've been using it in some form for almost a decade and never experienced problems with fish, even when being relatively cavalier about it's application.

I do wonder how many of the LC horror stories are misdiagnoses or downstream issues, simply because it can be so difficult to pinpoint problem sources in this hobby.

The accumulation of Lanthanum is an interesting concern. I'd love to hear what @Randy Holmes-Farley thinks of that and if there's a solution other than regular water changes to keep it at bay.

I'm in the same boat. I mix up 5ml to 500ml and dose as needed.
I was under the impression that once the lanthanum was bound to phosphate it was inert and non soluble, I suppose that it's possible that there is more free floating LC than bound if it's got nothing to bind to.

 

[djkms]

Interesting side note:
I was dosing 8-10ml per day of Elimi-NP to reduce PO4 previously which is the about same amount of PG I dosed to reduce PO4 currently.

 

[rishma]

I am sure it is a combination of both. At some point once i get this regimen stable for a month I could stop ammonia dosing for a week or 2 and test every couple/few days and see how that affects phosphate.

I do have to dose ammonia though because, as to Randy's point, this is dropping NO3 at a much higher rate then PO4. That being said it is obviously dropping PO4 as well which I was never able to accomplish with vinegar alone and TM products are not cost effective for me with a 600 gallon tank.

At the end of the day though, I am not trying to run a controlled test to find out exact consumption rates of PG and/or ammonium bicarbonate between NO3 and PO4. I am just trying to find a carbon source that shows to be effective at removing phosphate, regardless of the nitrate consumption. I was dosing 250ml vinegar daily and no reduction in phosphate. My filter socks would clog almost daily. Now I am dosing 8ml of PG, last filter sock change was 5 days ago and see a phosphate reduction which I never saw with vinegar. How much of it is the ammonia bicarb dosing? Hard to say for sure but I would bet its skewed toward the PG for sure. What I can say is 8ml of PG is more effective then 250ml of vinegar at reducing NO3/PO4 in my system.

I am just trying to take it slow as I have a lot of livestock in my 600 and don't want to experiment too fast too much with my baby ;)

Makes sense. Did you ever try ammonia with vinegar?

In the past I have able to lower phosphate by dosing nitrate and vinegar. Consistent with your experience, nitrate was dropping a lot, when I started dosing it the nitrate stabilized and the phosphate started to come down.

 

[Curiousbranching]

I think that only when you completely remove GFO and ammonia from the system will the results be truly accurate. I’m really looking forward to your next results.

 

[bubbgee]

I am not sure if different types of carbon dosing can really target phosphate, I’ve never seen a good explanation for that claim.

HOWEVER…

I am able to manipulate up/down and stabilize my phosphate by adjusting my dose of NP Bacto Balance. It is carbon dosing but also has nitrogen and phosphorus. I don’t know exactly what it is, which is usually a no-go for me, but it works very well and is inexpensive.

Also, many of us have seen that the use of ammonium bicarbonate results in phosphate reduction. Those that have tried it tend of to have low nitrate systems, so I cannot say it applies in all cases. I suspect the affect might be more pronounced while carbon dosing.

I dont dose phosphorus, but i hear great things about it. Any impact you are seeing to coloration or health?

 

[djkms]

I think that only when you completely remove GFO and ammonia from the system will the results be truly accurate. I’m really looking forward to your next results.

Agreed. I was able to pull off my reactor just now so no GFO is currently on the system. I am going out of town for the rest of the week but when I get back I will switch out my ammonia bicarb to my sodium nitrate solution and dose that in its place to prevent my NO3 from bottoming out.

More results to come!

 

[djkms]

Makes sense. Did you ever try ammonia with vinegar?

In the past I have able to lower phosphate by dosing nitrate and vinegar. Consistent with your experience, nitrate was dropping a lot, when I started dosing it the nitrate stabilized and the phosphate started to come down.

Trying to get off vinegar. I vinegar dosed in my previous 210 and it just slimed up everything. It was starting to do the same in my 600. Adding ammonia would mean I would just have to add more vinegar.