# Is there a natural and cheap way to lower phosphates?



## Gizmo

I've been testing my tanks the past three days straight (doing a week-long daily testing regimen to see how my tanks are doing). Here's my situation on my main (29 gallon) tank:

Today -
pH 6.8 (drop checker is green)
ammonia 0.25 ppm (I'm guessing it's zero since I'm using an old API test kit)
nitrite 0 ppm
nitrate 5 ppm
KH 6 degrees
GH 7 degrees
phosphate 2 ppm

My ten gallon measures the same, save for an elevated pH (7.6) since I'm using less-effective means of injecting CO2.

The phosphates are elevated and are coming from my tap. Is there a natural way of lowering them? I'm not about to go and waste my money on packet after packet of Phos-Zorb or any sort of pet supply store solution. I wouldn't worry about them, except that I've heard RCS don't like elevated phosphates.

Thanks in advance for your thoughts.


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## jrman83

Plants, plants, and more plants. Is it coming from your substrate? Water changes with RO water occasionally will help. Pretty easy to do with a small tank. I'd get the fastest growing plants I could find and load the tank. 1 or 2 fast growers in there may not be sufficient.

I used to think the same thing for my ammonia test. After my tank was loaded with plants, mostly Wisteria, I never saw .25 again. Now that all of my tanks are loaded, I never see it. I mean loaded though. Another way to see if it is a false positive is to stop feeding for 4-5 days or test your tap with it.


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## Gizmo

The tank already has a TON of plants. Three 1' tall giant hygros, a tiger lotus with about 15 pads and two on the way, three 1.5' wisteria plants, two 1' crypts, some riccia moss and frogsbit. I'm having to trim weekly or the plants will grow right up out of the water. I'm not worried about the false ammonia reading - I know it's zero, I'm just concerned about the phosphates. They have come down 0.5 ppm over the last three days since my last 33% PWC. I've stopped dosing fertz except nitrates, potassium, and Plantex CSM+B. Could I get away with lowering my PWC to 15%. or would that cause an overdose on my fertz?


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## jrman83

EI? If you are dosing mono-potassium phosphate, cut back a little. Could be an invite for BBA though. Plus, I only see one nutrient hog (Wisteria)....could be more, just not sure.


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## Gizmo

I'm not dosing monopotassium phosphate - my potassium comes from K2SO4. I have KH2PO4 but I'm not dosing it at all. Just KNO3, K2SO4, and CSM+B.

To the extent of my knowledge, the hygros are hogs as well. At least, they grow as if they are hogs.


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## susankat

About the only way I know of reducing the phosphates since its in your tap water would be to use ro or use the phosphate pads. I don't think the plants can take up that much phosphates. High phospates can also cause cynobacteria to start in the tank.


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## Gizmo

Definitely seeing the cyano bacteria, if it's a brown fuzzy type of stuff that gets everywhere. Might have to invest in an RO unit...


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## Auban

adding organic carbon can remove phosphates. the safest way to do this would be using flourish excel. you could also look up the vodka method and try that. it is most often used in saltwater tanks but works just fine in freshwater.


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## Gizmo

I'll have to take a look at that. Are there any other ways besides Excel (which is expensive from what I hear) and the vodka method? Where's a good source for the vodka method?


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## jrman83

Most I know, don't dose K2SO4 anymore. They use gh booster in place of it and only do a once weekly dose. I know Tom Barr stopped recommending it some time back. Potassium is also in KNO3.

How does Excel remove phosphates?


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## Auban

Vodka Dosing by 'Genetics' and 'Stony_Corals' - Reefkeeping.com

i have used sugar in my freshwater tanks for about a year or so now with excellent results. it seems that it really doesn't matter what the source is, just about any carbon that bacteria can metabolize works. i really think its only a matter of time before this becomes popular in the freshwater hobby as well.


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## Gizmo

I'll look into the GH booster, but my GH is already 7 degrees which if I remember correctly is right on. I'll just stop dosing the K2SO4. Is there another way to add potassium besides K2SO4 and KH2PO4? I dose KNO3, not sure if that's enough potassium though....


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## Gizmo

It looks like the carbon dosing will lower nitrogen levels as well, which I really don't want since mine are nearly zero without dosing the fert.


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## Auban

excell removes phosphates in freshwater the same way vodka does in salt water. the long story made short is that it feeds bacteria that convert phosphate and nitrate into a gaseous form, which then dissipates from the tank little by little.


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## Auban

phosphates in your tap water... your best bet might just be that RO unit...


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## jrman83

If that is the case, then I have never heard of it being used as a method to control phosphate levels. Planted tank keepers dose with phosphates and Excel.....so these have been working against each other? 

I need to contact the SeaChem guy on here and see what he says. Not saying you're wrong, just never heard of it before.


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## Auban

i thought about that when i started realized that i was adding sugar to my tank a while ago. i noticed something however, when i add just phosphate and nitrate, i get bacterial blooms, as one would expect. when i use them together with excel or sugar, i dont, the water is crystal clear. i have also noticed that my faster growing plants dont like excel or sugar.


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## James0816

Well...If you like floating plants...look at Azolla. Loves phosphates.


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## Gizmo

James0816 said:


> Well...If you like floating plants...look at Azolla. Loves phosphates.


Thanks! Do you know where I can get any?


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## James0816

You can check with a pond supply store. They may be able to track some down. I see people selling it from time to time online.


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## Gizmo

Tested my water last night, got the following readings:

pH: 7.0
ammonia: 0.25 ppm
nitrite: 0 ppm
nitrate: 5 ppm
phosphate: 1 ppm
KH: 10 degrees (up 4 degrees in 24 hours, and I retested to be sure)
GH: 8 degrees

I've got about 1.5" of organic sphagnum peat moss as the bottom layer of my tank, with API Laterite on top, topped off with 1.5" Fluorite. Would the peat moss be elevating my KH? I know bob always says it "buffers pH", but isn't KH a measure of the buffering capacity?


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## beaslbob

This bob says IME kH stayed constant (4 degrees) for years in my planted tank with peat moss in the substrate.

As the plants take off pH will rise (less carbon dioxide) and as they consume nitrates they do return carbonate ions (KH rises).

But then at higher pH (less carbon dioxide) they can use carbonate for their carbon source. So perhaps KH will go back down as pH rises.

(note: IMHO always measure pH just before lights out. It will start the day lower and rise after the lights come on.)


Looks like the phosphate is trending down also.

If you don't have any cyano/algae problems I would say just keep doing what you are doing.

If you do have cyano Kill the lights and stop adding fertz and stop feeding any fish for a few days until the cyano/alage dies off. The resume with less lighting less fertz, less feeding so the cyano /algae stays away.

Hopefully the nitrates will initially bump up then both the nitrates and phosphates will start down to 0 again.


Most importantly if your fish are healthy and you don't have algae/cyano don't change anything based upon what some test says.

my .02


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## Gizmo

I have cynobacteria, but my fish and inverts are healthy and relatively happy.

I light with a 24" 48W T5HO with 1 10,000K and 1 6700K bulb for 12 hours a day. I have a full glass hood on as well. Lux measurements at the bottom of the tank are at about 100, which when converted to PAR using conversion constants I dug up online for my bulbs puts the bottom of the tank at about 30 PAR. Top of the tank is easily 80 PAR.

I dose KNO3 for nitrates, Plantex CSM+B, and ferrous iron gluconate. Stopped my K2SO4 on Ben's suggestion.

I'll cut back on my feedings, I do tend to OD on the food to get enough to my bottom dwellers, especially my ADF's.

My pH swings from about 7.2 in the morning to 6.8 at night. Drop checker is green throughout the day.

I'll be testing again tonight.


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## jrman83

Your water measures what mine does (nearly) out of my tap. My ph is 8.2. I add 50% RO. I think your ph doesn't matter much, as far as the fluctuations go, when you are injecting CO2. Or more correctly, it is nothing I concern myself with as long as I can keep the drop checker in the green zone or a little toward the yellow side. With 50% weekly water changes, nothing in the water is a concern really....to me anyway. I let my fish tell me if something is wrong.

Cyano is not a good thing to have in your tank. It can be caused by low levels of nitrates - even if you are dosing them. A blackout may work, some say it doesn't, since it really isn't an algae afterall. I did a 4-day complete blackout to get rid of some other algae including cyano, a while back. It took care of the other algae, but about half of the cyano remained. Results vary I guess for blackouts. Peroxide treatments work as do anti-biotics.

Also, I don't think I ever said to stop dosing K2SO4. I only said that the method out there now is to dose gh booster in it's place once a week. It has all the main ingredients of K2SO4.


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## Gizmo

I know you didn't say it specifically, but I figured it was a good thing to do I guess.

So, ways to kill cyno are as follows:
1. Dose more nitrates, and try and reduce phosphates
2. Lights off, no fertz, no food for the weekend (I'll be going to Vegas, so it'll be easy).

2 sounds like the most effective way to kill it, and 1 sounds like a good way to make sure it stays gone. Am I right along those lines?


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## jrman83

Increasing nitrates will not kill cyano. It may prevent it. I only know that low nitrates can be a cause. I assume there are others. 

You can use peroxide, anti-biotics, do a blackout, or manually remove. Blackout worked for me to the point the rest was easily removed by hand.


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## Seachem

Hey everyone, Jrman83 asked us to chime in on using Excel to reduce nitrates and phosphates. The carbon components used in Flourish Excel are quite different from those of simple sugars and alcohols, such as vodka. In our studies with this product, we have seen no indications that bacteria are capable of utilizing the carbon in this form. If there is a decrease in nitrates or phosphates when using Flourish Excel, it is more likely that the plants are using more nitrogen and phosphate due to a faster growth rate. 

In your case, I think the best way to reduce the phosphates in you tank would be using RO water instead of the tap. This would give you much better control of what minerals are in the water and allow you to build the ideal water for your system.


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## beaslbob

thanks to seachem for responding.

very interesting stuff on Excel which I understand is an excellent product.

While it is absolutely correct that with a water change operation you can reduce phosphates with ro/di water, I personally believe that amount is very small compared to the nitrates and phosphates being generated by the bioload.

But then I don't have any scientific experimental data to back up that claim either.

Just anecdotal observations of several aquariums both salt and fresh running for years with untreated tap water using plant life. Both nitrates and phosphates were unmeasureable.

Perhaps that works because of the combination of plant life, tap water, and no water changes.


still just my .02


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## Seachem

You are very welcome!


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## Gizmo

beaslbob said:


> While it is absolutely correct that with a water change operation you can reduce phosphates with ro/di water, I personally believe that amount is very small compared to the nitrates and phosphates being generated by the bioload.


I've been told that the phosphate levels in the tank should be roughly 10% of what the nitrates are. I'm attempting to elevate my nitrates above 5 ppm with KNO3, but ATM the phosphates are 20% what the nitrates are.

And that's after a week of the water sitting there. Fresh out of the tap, it's 40%


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## beaslbob

Gizmo said:


> I've been told that the phosphate levels in the tank should be roughly 10% of what the nitrates are. I'm attempting to elevate my nitrates above 5 ppm with KNO3, but ATM the phosphates are 20% what the nitrates are.
> 
> And that's after a week of the water sitting there. Fresh out of the tap, it's 40%


Sounds like EI or redfield ratio stuff where it takes 16 nitrogens for every phosphate ion for plant growth.

What I do is let the plant life expand and if I get cyano then kill the lights. then adjust lighting and feeding so the cyano stays away.

After a few months both nitrates and phosphates are unmeasureable.

I also feed very lightly and only once per day.

my .02


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## Seachem

Gizmo said:


> I've been told that the phosphate levels in the tank should be roughly 10% of what the nitrates are. I'm attempting to elevate my nitrates above 5 ppm with KNO3, but ATM the phosphates are 20% what the nitrates are.
> 
> And that's after a week of the water sitting there. Fresh out of the tap, it's 40%


Thats where your problem would be solved by the RO water. While some phosphates are going to be produced within the tank naturally, most of them are coming directly from the tap. Using RO would do away with the 40% and allow you to hit your target of 10% by either dosing or naturally if there is enough produced in the tank.


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## Seachem

You are very welcome, as always!


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