Phosphate Measurement

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I have been heeding your advice and trying to increase my phosphate levels in the water column (minor hair algae and some diatom type on glass and anubias old leaves). I have been using seachem and dosing through a peristatic pump at 20 mls a day for a 180 with a w/d sump. In wcs I add seachem to get the water at .5 ppm, but whenever I check the column I cannot get a reading over .2 ppm using a Lamont kit.

Are the plants just taking it in faster than I can check or am I underdosing? I have been resistent to use dry ferts because of my daily dosing system fearing that I will have to continually agitate the dose.

I my real life we use a injection system on a golf course I used to manage to fert the turf and it must be continually agitated to maintain consistent macro delivery numbers.

Anyone's insights appreciated.

84.5 F and ph of 6.65
CO2 at 20 to 25 ppm
Nitrates at 8 to 12 ppm
Phospates at 2 ppm
4 mls of Flourish Fe daily

Light at 3 wpg for 4 hrs, 2 wpg 3 hrs. and 1 wpg 3 hrs.

 

[Laith]

Re: Phosphate Measurement

20ml of Seachem Phosphorous in a 180g tank (assuming 155g water volume) is around 0.16 mg/l of PO4. Using KH2PO4, I dose around 0.85 - 0.9 mg/l per day.

And IMO your NO3 levels are a bit low. I like to aim for 25mg/l but 15 - 20 mg/l is good. The goal is to avoid it bottoming out.

I use KNO3 and KH2PO4 dry powders mixed into a solution and dosing using autodosers. I don't have any issues with precipitates or concentrations so this method isn't a problem.

You also seem to only be dosing Seachem Flourish Fe. This is *only* Fe and contains no other trace elements. I would dose standard Flourish along with the Flourish Fe.

Get your CO2 up to a consistent 30mg/l during the photoperiod.

And I don't quite understand your lighting schedule. Is this a total of 10 hours with the first four hours at 3wpg, then three hours at 2wpg and then three hours at 1wpg? If so, this is a bit different than the "normal" noon burst method which starts out low, peaks in the middle of the photoperiod and then finishes low again (eg 3 hours at 1.5wpg, then 4 hours at 3wpg, then 3 hours at 1.5wpg). It may not matter; I just haven't heard of it being done this way before.

 

[[email protected]]

Re: Phosphate Measurement

Thanx for the response. First this is a Discus tank and I need to keep NO3 at around 10ppm. I do add Flourish at a rate of 3 ml per day along with Flourish FE at 4 mls per day.

I was calculating my phosphate additions on the basis that I have a starting point of .2 ppm of phosphate and I add another .8 ppm if I look at it as a cumulative addition over the week. Every water change includes the addition of .5 ppm of phospate. When I test the wc water is reads right on, but when I test the tank even right after a wc it never gets above .2 ppm. My WC are 35% three times a week.

I was told that phospate is quickly absorbed or precipitated and that accurate measurements in the water column are problematic in a dynamic system.

From your comments it seems on a weekly basis with wc additions aside 140 mls of Flourish Phosphate is insufficient even though the directions infer I should be in the .8 range. I may move to wettable powders if as you experience precipiatation is not a problem.

Lighting is as you thought I start at 1 wpg for 1.5 hours and progress to the end of the day back at 1 wpg for the last 1.5 hours.

Are you using EI or conducting measurements?

 

[Tom Barr]

Re: Phosphate Measurement

Dan, do this: it's cheaper and simple:

After each 35 % water change(or 3x a week):

TMG(Or flourish + maybe 10mls of Fe++) , 40mls
2 teaspoons KNO3
1/4 teaspoon of KH2PO4
GH (SeaChem of Greg's GH booster): 1 teaspoon

Crank the CO2.

That will add about 10ppm per dose of NO3.
Plenty of P, K, Ca, Mg, traces.......

Now you can fill up a dosing reservior and set the dosing pump to dose 100mls a day and add say enough water for 2 weeks(1400mls) and add 6 the above amounts if you wish.

I'd keep the Traces seperate when dosing auto etc and use a seperate dosing pumps etc. TMG will mix better with PO4 than Flourish, and the Fe will persist longer in the plant bioavailable form.

The chealtor for Flourish weaker, which means the plants does not need as much energy to abstract the Fe, but..........you only need 250,000 N for every Fe, so there's not much extra energy that the plant has to spend to mee the Fe demands, main thing is just to have low levels around most of the time or reduce that and has less light/growth/demand.

Regards,
Tom Barr

 

[[email protected]]

Re: Phosphate Measurement

Thanks Tom, I like the simplicity and will give the new regime a try and monitor the results. My only hard parameter is the NO3 levels for the wild Discus. Right now w/o any additional NO3 I go from 8 ppm after WC to 13 ppm before a WC. These guys are sensitive to NO3 so I am a little leary of adding add'l. What do you think?

Dan

 

[Tom Barr]

Re: Phosphate Measurement

Simple is good.

I have clients with discus that make your wild ones look "hardy". Monterey Bay Aquarium keep 15 Wild Adults in a 500 gallon tank for years at 30ppm.

It's not NO3, it's NH4 from all the food and by the time the bacteria get done, it's measured as NO3.

Overloading high feeding rates vs adding inorganic NO3 are two entirely different stresses on a fish.

Few Discus folks have test kits able to measure the difference between 8 and 13ppm accurately.

1 ppm of N-NO3 is 4.4ppm of NO3.......and that's with a Lamotte......

So the difference is slight.
Low levels of NH4 is likley not good for anything.

I've had over 120ppm with wild SA fish, I lost no fish(2000 of them and 30 species), but lost a fair amount of shrimps. Discus were fine.

I do not suggest that, but you sound like you have the discuscentric fear thinking.

Folks routinely add KNO3 above 10ppm and breed Discus in planted tanks.

I've not seen any sensitivity in any SA soft water fishes to NO3 at 30-40ppm ranges ever.

Regards,
Tom Barr

 

[TexasRock]

Re: Phosphate Measurement

Dan,

What do you use to get your pH that low?

Keith

 

[[email protected]]

Re: Phosphate Measurement

Yes Tom, I do confess to the discuscentric malady. New to keeping them and err on the neurotic side. I do use a Lamont so I think my measurements are fairly accurate anyway I will give your regime a shot and see if the GDA and thread algae calm down. I have some super phosphate product in the basement and will start dosing that in conjunction with KNO3.

Keith, I keep my KH at 5 and use a DIY CO2 reactor controlled by a Neptune unit 24/7 to keep the ph steady and CO2 in a decent range. ph then moves from 6.65 to 6.68 all the time. That part of the experiment is easy to control.

Dan