advice on dosage

[loverans]

Hi I am new here. My tank is 52 us gallon, with 50 fishes, 10 malayan shrimps and many plants. PH 6.8, Kh 4 and Co2 about 3bps. 1 golden ram died last week and another this week. Tested water yesterday and noted my nitrate level was over 100 ! I started dosing KN03 (1/4 tsp) & Kh2PO4 (1/8 tsp) on alternate days. Other days I dose P (1/2 tsp) and 2ml of fertiliser (china brand). Weekly change of water 30%. Could it be my dosage wrongly or the water changing too little ? What should I do now ? Really appreciate your expert advice. thank you.

[medicineman]

How old is your tank. How heavy is the plant load and of what type. How high is your level of lighting. You may have added too much fish load under too little time. Should be small bio load added over longer time for the tank to counterbalance. You may want to half the KNO3 and KH2PO4 dosing and give it twice a week, but still it depends on the tank setup itself. The olny thing I see for nitrate level to reach 100 is not from your fert (which can only reach max 15-20 ppm from a whole week of dosing), but from ammonia breakdown due to fish load or uncompleted tank cycle.

[PeterGwee]

Unless you calibrate the test kit with respect to standard solutions, you simply cannot trust those hobbyist kits sold in LFS. It might be the NH3/NH4 getting to the fishes. Doing 2x large weekly (50% or more) water changes, adding zeolite/carbon to the filter and packing the tank with loads of plants (newbies always fail to do this! Do not wait for things to grow in!) would prevent the NH3/NH4/NO2 poisoning.

Regards
Peter Gwee

[loverans]

My tank is about 9 months. I tested nitrate last month and it showed about 20 ppm. Fishes are ok as no death cases at that time. No new fishes were added since then . I feed them twice in the morning and evening. Is there heavy fish load and should i move some to another tank ?Should I continue feeding or stop feeding after large water change ? I should continue the dosage, right ? Thanks really for your guidance.

[|squee|]

Other days I dose P (1/2 tsp) and 2ml of fertiliser (china brand).

What does the 2ml of fertiliser contain?
What is P? Potassium?

I also suggest increasing your weekly water change to 50%. Is there a picture of your tank we can take a look at?

[loverans]

Its K2SO4, not potassium. I dont find label stated content of fertiliser. The name is hormones for seaweed ( with a dolpin logo) sold at NA. Have change 50% water , measure nitrate drops to 30ppm. Thanks all for your advice.

[|squee|]

Well you got nitrogen, you got potassium, you're only missing phosphorous. Try getting KH2PO4 from NA and dose a pinch of the powder 3 times a week.

[uklau]

Since we are on this topic, may I now what do we get from dosing KNO3 & KHPO4? Am I right to assume that both contribute to K? In addition, KNO3 contributes to NO3 & KH2PO4 contributes to PO4? Thanks.

[|squee|]

KNO3 provides potassium and nitrogen in the form of nitrate.
KH2PO4 provides potassium and phophorous in the form of phosphate.

Both contribute potassium

[medicineman]

Both contribute potassium...

...which is usually not much enough to fulfill a tank's need. That is why we add K2SO4 or KCl to reach the desired level of K.

[uklau]

Thanks, Terence but it's too concise for my poor chemistry brain to understand. Mind elaborate some more?

[loverans]

Need advice again. I change 50% water on sunday. Stop dosing KNO3 & KH2PO4. I feed once only on Monday. I test water this evening, it rises from my last measurement on Sunday of 30ppm to 50ppm. Does it mean that my fish load is high as such Nitrate high ? Since Nitrate is high, can I stop dosing KNO3 and only dose Kh2PO4 and other micros nutrient ? Thank you.

[dc88]

Have you tested your tap water ?
Stop KNO3 for a while and monitor.

[|squee|]

Thanks, Terence but it's too concise for my poor chemistry brain to understand. Mind elaborate some more?

Sure.

KNO3 is potassium nitrate. Nitrate consists of nitrogen and oxygen. Thus KNO3 adds potassium and nitrogen to the water.

KH2PO4 is potassium phosphate. Phosphate consists of phosphorous and oxygen. Thus KH2PO4 adds potassium and phosphorous to the water.

Altogether they add potassium nitrogen and phosphorous, the three elements plants consume more of. Other nutrients are easily settled with half dose of Seachem Equilibrium and commercial trace elements.

...which is usually not much enough to fulfill a tank's need. That is why we add K2SO4 or KCl to reach the desired level of K.

But the author of EI says that you do not need K2SO4 nor KCl

[medicineman]

Ah.. mr barr's cs reasoning (and research). I'll investigate and buy that
thanks for the link.

I've been intentionally dosing far smaller amount of K than what traditionally people suggest (something like 5-10ppm compared to 20-30ppm) and did not see any ill effect to the tank. Perhaps it is not really as necessary when you've given K from KNO3, KH2PO4 and some more from certain liquid ferts. But then again some people have had intentionally escalade their K level to nearing 100ppm in order to achieve something in their show tanks. I've still got no idea the use of such large amount of K, but one of these days I will try it out and see any effect.

[PeterGwee]

Your test kit is rubbish, you really need alot of NH3 to get that amount of NO3 in that short time and that means you would have a tank of dead fish/shrimps which you don't. If you really want to use test kits, you need to invest in good ones like Hach (Over $130++..) or LaMotte or get those Spectrometers (most expensive but no need to use eye-balls to gauge colour differences.).

Look at the plant growth and health rather than trusting the test kit result that much. I went that way before and can tell that you are better off doing the estimative index way and focus on the CO2 based on visual cues once you do a simple dial in using pH/KH or get those quality test kits (calibrate them as well using standard solutions of 1ppm, 3ppm, 5ppm, 10ppm).

Regards
Peter Gwee

[fi5hkiller]

I have many experience with cheap and lousy NO3 test kit and all give me weird results.
in fact a simple method I using to test for NO3 is smelling.
if NO3 is high, you bet your tank is going to be STINK!! but with planted tanks, this is very unlikely.

[uklau]

Thanks, Terence. Is the NO3 from KNO3 the same as NO3 converted from NH3 by the BB?

[|squee|]

Yeap. But in a planted tank ammonia gets taken by plants pretty fast (I read in Diana Walstad's book plants prefer to take up ammonia first compared to nitrate) so we supply nitrogen through nitrate. Tom Barr has also proved that ammonia can cause an algae bloom so that's why we don't add ammonia

[loverans]

Hi Peter, if I read it correctly, I should continue to dose macro and micro nutrient and ignore those test kits result on nitrate. Do a weekly water change of 50% or more. Does that mean nitrate will be at a acceptable level ? How as a newbie will know if nitrate has reached beyond acceptable level ? really appreciate your sharing. thanks