Phosphates, and the API test

[StephenP2003]

I can't tell if I have too much, or too little, or what. According to the phosphate liquid test from API, I have 2 ppm phosphates in my tap water. The test registers the same in all my tanks, regardless of my feeding or fert dosing (some tanks get flakes more than others, some get live baby brine, some get more repashy, frozen, etc. -- some tanks get easy green, others just get potassium and iron). 

I even have a bag of Phosguard in my 90G filter as an experiment. It's been running with the phosguard for about 45 days, with no change in phosphate levels.

I've had issues with a couple different plants, like dwarf sagg and hygrophila, that look like phosphate deficiency (green spot algae on yellowing leaves), but test shows 2ppm still, which by all Google indications is fine if not high.

So, how accurate is that API test really? Is it even testing for the right thing, or is the phosphate in my tap water not "absorbable" or something? I did do a control test on distilled water and got zero phosphates.

[Mike]

It sounds suspect to me. Maybe you can try dissolving some common garden fertilizer (just make sure it the P in its NPK values isn't zero) or bone meal into a cup of water and test against that. If the phosphates aren't high, something is wrong.

Alternatively, you can get a different test kit and cross-check the results.

[tattooed_meany]

I used to do water chemistry testing for large industrial complexes and had many times run across differences in test results that didn't make sense.

Look into age of reageants as a start. Some test kits may sit on shelves for extended periods of time so even though they are "new" to you they may be quite old. I have had  this happen on a few ocassions. if you can cross-check with another or a fish friends testing reageants against your own results.

I have also bought reliable testing kits only to have bad reageants in the kits. Don't rule anything out when it comes to quality controls with some companies.

Good Luck, hope you get to the bottom of this.  👍

 

[DaveSamsell]

@StephenP2003, Was wondering if you did any more Phosphate testing?  Also, what are your Nitrate levels generally?

Am new myself to the API Phosphate test and found it to be very accurate, with my particular purchased kit, from the Co-Op.

My expiration dates on the bottles are a couple of years from now and the kit worked great; but a good expiration date on bottles is obviously "not an absolute guarantee" that the chemicals are indeed unexpired or not having another particular issue, for whatever reason.

What I found interesting is that you did get a big difference in testing result when you used 'distilled water' .  

 

As a comparison:

I have 0 level of Phosphate in my well/ground water and each of my aquariums did test slightly differently.

I purposely dose some of my planted tanks with extra Phosphorus, since some of my plants where experiencing symptoms of a Phosphate deficiency; and the dosing did help.  It was like some leaves had random brown, soggy patches on them; so a difference in my plant symptoms, compared to yours .

The aquariums with the symptoms had Phosphate readings of less than one half (<1/2 ppm) , originally.

The aquariums are fed, relatively lightly, so maybe not enough Phosphate was getting into the tanks, perhaps.  

Am also learning about how plants can absorb Phosphate and store it, from the water, which is interesting in itself.   

One of my heavily planted aquariums, Phosphorus levels always reads low, even though it's dosed well enough.  Might be the plants taking out the nutrient that quickly, which I found to be a little strange.

The level of Phosphate I try to maintain is about 1 ppm and the plants are doing better, for me anyway.

Hope some of my experiences help.  Again, am learning about all of this as well.  😊

 

 

[StephenP2003]

20 minutes ago, DaveSamsell said:

@StephenP2003, Was wondering if you did any more Phosphate testing?  Also, what are your Nitrate levels generally?

Am new myself to the API Phosphate test and found it to be very accurate, with my particular purchased kit, from the Co-Op.

My expiration dates on the bottles are a couple of years from now and the kit worked great; but a good expiration date on bottles is obviously "not an absolute guarantee" that the chemicals are indeed unexpired or not having another particular issue, for whatever reason.

What I found interesting is that you did get a big difference in testing result when you used 'distilled water' .  

 

As a comparison:

I have 0 level of Phosphate in my well/ground water and each of my aquariums did test slightly differently.

I purposely dose some of my planted tanks with extra Phosphorus, since some of my plants where experiencing symptoms of a Phosphate deficiency; and the dosing did help.  It was like some leaves had random brown, soggy patches on them; so a difference in my plant symptoms, compared to yours .

The aquariums with the symptoms had Phosphate readings of less than one half (<1/2 ppm) , originally.

The aquariums are fed, relatively lightly, so maybe not enough Phosphate was getting into the tanks, perhaps.  

Am also learning about how plants can absorb Phosphate and store it, from the water, which is interesting in itself.   

One of my heavily planted aquariums, Phosphorus levels always reads low, even though it's dosed well enough.  Might be the plants taking out the nutrient that quickly, which I found to be a little strange.

The level of Phosphate I try to maintain is about 1 ppm and the plants are doing better, for me anyway.

Hope some of my experiences help.  Again, am learning about all of this as well.  😊

 

 

I've still been testing. Always 2.0 ppm. The shade is just a hair lighter out of the tap -- more than 1.0, a little less than 2.0ppm. I also feed flake, so phosphates come from that. I think the test is good, and phosphates are just not the problem.

@Bentley Pascoe helped me out by looking at some pics of my struggling plants and suggested dosing trace, or that it could be nitrogen or magnesium deficiency. I'm always at a good nitrate level -- the tank in question is sitting at 40ppm right now actually (getting close to waterchange day).

I dose Potassium Mon/Wed/Fri, and Trace and Iron Tues/Thurs in all my tanks. They are seachem products except the iron. I dose per the volume suggested on the bottles, and I'm starting to think I've just been dosing too little for my plant situation in this big tank. It's a 55-inch tank with plants practically end-to-end/front-to-back -- heavily planted. And seachem products seem to be more dilute than necessary.

 

[DaveSamsell]

1 hour ago, StephenP2003 said:

I've still been testing. Always 2.0 ppm. The shade is just a hair lighter out of the tap -- more than 1.0, a little less than 2.0ppm. I also feed flake, so phosphates come from that. I think the test is good, and phosphates are just not the problem.

@Bentley Pascoe helped me out by looking at some pics of my struggling plants and suggested dosing trace, or that it could be nitrogen or magnesium deficiency. I'm always at a good nitrate level -- the tank in question is sitting at 40ppm right now actually (getting close to waterchange day).

I dose Potassium Mon/Wed/Fri, and Trace and Iron Tues/Thurs in all my tanks. They are seachem products except the iron. I dose per the volume suggested on the bottles, and I'm starting to think I've just been dosing too little for my plant situation in this big tank. It's a 55-inch tank with plants practically end-to-end/front-to-back -- heavily planted. And seachem products seem to be more dilute than necessary.

 

@StephenP2003 , I have a schedule that personally works for me.

In my heavily planted aquariums, I dose Easy Green after a water change, to actually bump up my nitrates a bit.

Then, I switch to Easy Iron, combined with Seachem Trace on one day, then alternating with Seachem Flourish (Comprehensive, Potassium & Phosphorus) combined on the next day.

I have medium light & dose twice the " recommended " dosage, several times per week.  All I can say is that it works for me as I feel the Seachem products are a bit diluted.

Have been doing this schedule for awhile now and still am waiting to actually grow some algae.  

Is it the best way I ask myself, maybe\maybe not, but it has been working, so haven't changed the schedule.

Sometimes, when my plants are really growing, I'll dose even a bit more at times.

I look at it as feeding fish.  The more fish the more food is needed.  Same thing with fertilizing plants, IMO.  

There are probably other products & methods to get me there, but have been too lazy to try them, lol.  

[Bill]

I just searched here for phosphate because I just tested with the API kit. I tested because I have some brown algae specifically in a 30 gallon that was setup about a month ago. I got a reading of about 3 ppm and I get about the same reading in all my other tanks, and tap water. Hmm...

[Bill]

I called a local fish shop that I like and asked them what they thought. They can't speak to the test accuracy, but they did say they use Seachem phosguard on all their tanks. 

[DaveSamsell]

5 hours ago, Bill said:

I just searched here for phosphate because I just tested with the API kit. I tested because I have some brown algae specifically in a 30 gallon that was setup about a month ago. I got a reading of about 3 ppm and I get about the same reading in all my other tanks, and tap water. Hmm...

@Bill. Just seen your post and a couple of ideas came to mind, that may help.  

Did you ever test for Phosphates before and know a baseline?

Can you obtain water from a different source and test to see if there is any difference?   

Note:  Brown algae was very common in my tanks when some of them were cycling.  Seems like the brown algae was the first to appear and then it was outcompeted for nutrients by the green algae, etc.  

All the best....

 

Edited September 25, 2020 by DaveSamsell

[Bill]

Thanks @DaveSamsell! Yeah, I know it's definitely common and will eventually clear. This tank had a bit more, and it's annoying because it's coating some plants that aren't easy to clean off (val and ludwigia repens which were growing), so I figured I'd see if there was anything I could do to reduce. Silicates are low and all other parameters are good. I've never check phosphate before so when I saw the level I checked my other tanks and then the tap water and they're all the same, around 3, maybe a bit over.

[DaveSamsell]

1 minute ago, Bill said:

Thanks @DaveSamsell! Yeah, I know it's definitely common and will eventually clear. This tank had a bit more, and it's annoying because it's coating some plants that aren't easy to clean off (val and ludwigia repens which were growing), so I figured I'd see if there was anything I could do to reduce. Silicates are low and all other parameters are good. I've never check phosphate before so when I saw the level I checked my other tanks and then the tap water and they're all the same, around 3, maybe a bit over.

@Bill, Maybe you have some other water you can test, I.E. left over bottled water, etc, just to get a small sample and see if it's the test kit or not.  

3 ppm is high, no doubt.  

I had the same brown coating on plants as well.  Not fun to clean off.

All the best.......

[Bill]

@DaveSamsell thanks ... I thought I used the last of my bottled water when I made coffee this morning but found a bottle ... it's the test kit. All I can say is my phosphate is about the same if a tiny bit more than Trader Joe's Mountain Spring water.  

[Brandy]

Well, I have been going nuts here, thinking I also seemed to have really high phosphate in all my tanks--and +3ppm in my Seattle tap water?! I need to get some distilled water and test the test kit, I see. I am exceedingly suspicious, though the expiration date is 3/2023. 

Still. Question: What is the upper "safe" limit for phosphate? For fish? For plants? If I balance the other nutrients (increasing the N and K and trace) wouldn't my plants solve the problem, assuming it exists?

[DaveSamsell]

On 10/11/2020 at 12:42 PM, Brandy said:

Well, I have been going nuts here, thinking I also seemed to have really high phosphate in all my tanks--and +3ppm in my Seattle tap water?! I need to get some distilled water and test the test kit, I see. I am exceedingly suspicious, though the expiration date is 3/2023. 

Still. Question: What is the upper "safe" limit for phosphate? For fish? For plants? If I balance the other nutrients (increasing the N and K and trace) wouldn't my plants solve the problem, assuming it exists?

@Brandy, Have read about 1 ppm phosphate upper limit.  Typically, I keep my phosphate levels about 1-2 ppm, with zero problems.  Seems like my plants do better at that level.

Would imagine the exact number would vary for sensitive, freshwater inhabitants.   

Also, many folks use the 'nitrate' reading as a proxy, for other levels .  Have had mixed results with that theory.  

I.E. some of my aquariums have fast growing stem plants.  Seems like I can never add enough potassium to some of the tanks, LOL. 

The faster growing plants seem to out-compete the slower growing ones for nutrients.  

[Garren]

Defiantly a interesting read. I tested my water with the API Phosphate kit as well...found it interesting that my tap water is 2.0 PPM and the same results in my tank. Never really had a issue with algae except when I first stated my tank out. Now that the plants are established and growing well I don't have a issue with algae growth. I do have mollies and shrimp that probably keeping the algae at bay. None the less no matter what I do unless I use another water source then my phosphates will probably not drop below 2.0 PPM. I am not to worried as the high levels should not harm the fish but if a huge algae bloom happens that may cause a concern. 

Would like to see what others think about phosphate levels in the tank and what are the safe levels.