Removal of PO4

[b_goh88]

Hi,

Lately my tank is having alga problem and my PO4 is way too high. Did about 30% water change per week for the past 3 weeks but PO4 is still way too high.

Went to LFS to look for a PO4 removal. There are many to choose from: Sera, JBL, Seachem, and many other bands.
Seem like Seachem is the most cost effective, not too sure about the effectivenss of the product.

Any brother has use this before and what is your recommendation?

All these PO4 removal are like small pebble type and need to be placed in the filter for upto 6 months.
I also came across another PO4 removal from Baxter which is powder type and is added directly into the tank.

Anyone used this before? will it leak Al into the tank?

[Aeon]

What is the level of PO4? Singapore water have around 0.5ppm i think. You might want to know what is causing it to be high. Overfeeding? Decaying plants? Dead fishes?

Also PO4 less than 1ppm does not cause algae. it's only when the NO3 doesn't increase with PO4 then have problems. You also have not tell us what algae is it.

[vinz]

Actually, PO4 does not cause algae problems at all. If you have an abundance of PO4, most likely it means your plants aren't getting enough NO3. Basically, if your plants aren't getting enough NO3, they won't need PO4.

Increase the NO3 and you'll probably see a drop in PO4.

If you remove the PO4, your plants might suffer from lack of PO4.

You also need to consider where is all that PO4 coming from? Usually it's from our fertilisers or the fish food, but these are minutes amounts, unless you are seriously overdosing. Also check if PO4 is coming from your tap water. Lastly, check if your test kit is working properly or whether you are using/reading it correctly.

As Aeon asked, what levels of PO4 are you getting? I used to dose up to 2ppm of PO4 after water change to balance the NO3 being produced by my fish.

[b_goh88]

My PO4 is more than 10ppm (I used JBL PO4 test kit). I reduced my feeding, no dead fish, but some decaying plants that I tried to remove.

I measured my NO2 which is less than 0.03ppm (Tetra test kit), did not measure NO3. Algae is flat type on glass of the tank and on some of my plant.

[b_goh88]

Test kit is working fine. I checked with using tap water, reading is zero.

[vinz]

Well then, the source is fertiliser or fish food, so means your plants are not consuming PO4.

What fertilisers are you dosing?

[b_goh88]

I don't add any fertiliser other then Dupla Iron, daily dosage with Ehiem auto doser.

What must I do to make the plants consume PO4? Or what wrong that the plant is not consuming PO4?

What do you recommend for fertilisation? I used Dennerle (A Gold 7) before, and base is also Dennerle, my tank is about 10months old.

Check with Dennerle web site, the algra I've is Blue algra.

[Aeon]

Hey could be PO4 test kit failure. Since tap water is 0, then the reagent would not have any reaction. But when there is PO4, then it can be inaccurate. Very unlikely can hit 10ppm even with overfeeding and decaying matter.

If you have too much PO4 in the water without NO3, then you'll get Blue Green algae, according to the redfield ratio.

Determine what contributes to the PO4 in water. Could be plants cannot use PO4 as NO3 is lacking, as a result, plants are less healthy, melt, decay and contribute even more PO4. Could be overfeeding.

Try to do a water change, stir the water near the substrate a little to kick up the settled detritus. Wash the mechanical filter media to remove decaying waste.

Dose Potassium Nitrate. Look for other symptoms of plants. Is there yellowing? melting?

[b_goh88]

Thanks guys,

I did a water change (30% to 40%) last night. As what Aeon's advise, I stir the water near the substrate and also remove drift wood to suck out all settled detritus.
Filter media was washed last Wednesday, so I did not wash it this time.

I also removed as much blue algra as I can. Most plant look ok, tiger lily, java fern. Other plant don't look so health, some yellowing.

PO4 check is low after 1 hour, the last 3rd color on the left of the JBL chart (can't remember the ppm) .

I will be buying another new set of PO4 test kit and NO3 test kit, any good recommendation? Think of buying the US brand (something Pharmaceutical)

Any recommendation for fertilizer? As mentioned, I only add Dupla iron daily dosage and also add 5 Dupla basic fertilizer tablets every water change.

Appreciate you could advise where can I get potassium nitrate and how to use?

[illumnae]

i get my potassium nitrate in powder form from NA and just dose it dry by sprinkling it into the water...some people like to mix it with tank water first before putting it in to prevent fish from pecking at it.

as for the dosage, check out the EI dosing based on your tank volume. i dose 1.5 teaspoons for my 4x2x2 tank

[Quixotic]

What are you using as your filter media? Activated carbon?

[b_goh88]

My tank is 400l, how much potassium nitrate I need to add? Daily dosage or during water change?

I only use normal filter media with glass rings, no activated carbon or any other stuff.

[b_goh88]

I've gone through some of the past post on fertilizer.

K2SO4 1/2 tsp 3X per week (Opt)
KNO3 1 1/2 tsp 3X per week
KH2PO4 1/2 tsp 3X per week
Trace Element 30 ml 3X per week (SeaChem Fluorish, any other recommendation?)

Will it be better if I mix

K2SO4 1 1/2 tsp (Opt)
KNO3 4 1/2 tsp
KH2PO4 1 1/2 tsp
Trace Element 90 ml

and put them into a auto doser and dose the mixture (small dose) for a week?

[Aeon]

I'm using API (Aquarium Pharmaceutical Inc.) test kits also. Good value but you should calibrate, not sure how I don't.

Wah if after you sucked out the detritus phosphates becomes low, then it must be A LOT of waste there

You can follow the recommended dosages you read. But as for K2SO4 (Potassium Sulfate, used as Potassium supplement), I don't like it as it adds Sodium which plants don't use. Might affect the osmotic balance in plants (not so sure though). I personally use pure K type like Ferka Balance K or ADA Brighty K.

[b_goh88]

Thanks Aeon.

I did another check use my newly brought PO4 & NO3 test kit (API).
PO4 reading show 5ppm and NO3 is 0ppm.

After adding another 5 tablets of Dupla basic fertilizer.
Did another test (2 hours later) show PO4 = 5ppm and NO3 = 10ppm.
My older (JBL) PO4 test kit show again 10ppm.

Is there any test kit for potassium? I don't see it in most of the LSH.

From SeaChem web site, they also have Flourish Potassium. Anyone try this before?

[Aeon]

it's hard to overdose on Potassium. A little too much is fine. if you dosing KNO3, the K should be enough, else add KSO4 (sulfate). If you like me don't like the sulphur, use something like Ferka Balance-K or ADA Brighty K which is only K.

[b_goh88]

Measurement for NO3 is 20ppm 1 day after adding the K2NO3. KH is stable at 4dH. GH at 4dH, PO4 is still at 5ppm. Fe is 0.5ppm. CO2 is 26ppm.

Did not see anymore Blue Algra. Will continue to monitor as I've remove most of them last week.

Is it a must to add KH2PO4 now as my PO4 is 5ppm? Should I wait till PO4 drop below 2ppm?

Which is the important trace element should I add. Currently, I'm only dosing Fe from Dupla (Left over last time, checked still OK).

Thanks.

[Aeon]

My PO4 is 0.5ppm +- constant. But have to depend on plant mass. try this http://www.xs4all.nl/~buddendo/aquar...htm#calculator. Dose your NO3:PO4 to about 10 Redfield Ratio.

[PeterGwee]

Measurement for NO3 is 20ppm 1 day after adding the K2NO3. KH is stable at 4dH. GH at 4dH, PO4 is still at 5ppm. Fe is 0.5ppm. CO2 is 26ppm.

Did not see anymore Blue Algra. Will continue to monitor as I've remove most of them last week.

Is it a must to add KH2PO4 now as my PO4 is 5ppm? Should I wait till PO4 drop below 2ppm?

Which is the important trace element should I add. Currently, I'm only dosing Fe from Dupla (Left over last time, checked still OK).

Thanks.

Stop focusing on the test results from those test kits....you are not going to get much out of it. Dose base on the amount of light intensity you are giving to the tank. Dosage is the same per dose except for the frequency. CO2 is the main thing you should really focus on. Weekly large water changes would reset the water even if you overdose a bit. Main thing with growing plants is to make sure they are not limited. EI does that exactly except for CO2.

Regards,
Peter Gwee

[Aeon]

Oh yes water changes does not reset parameters to zero, it halves them (for a 50% WC). So without first using testkits to get a hang of how much to dose, it's hard to do guess work. But once you used to it and know how to observe, plants are the best indicators. I used to test every day but now I've stopped for a week already, unless I need to be sure.