N or K should be more? I'm CONFUSED!

[hypersushi]

Assuming one is having a 3WPG tank with fairly densely planted flora and a full tank fish load (ie. max fish load but not overcrowded), and the CO2 is 32ppm then the ideal N:P:K should be something like 5ppm to 10ppm: 1ppm: 20ppm? Am I right so far? Assuming I am dosing DRY, I give P a pass since the fish and excess fish food should cover it? Then let's look at the N and K.

Then using Chuck Gadd's calculator I arrive at N (1/4 teaspoon) and K (1 teaspoon). Have I erred somewhat? Coz I surf some sites and I find that K can be neglected???? http://www.aquaticplantcentral.com/f...ing-guide.html

I am following Rex's method but dosing all DRY. http://rexgrigg.com/dosing.htm

Please advise. I am soooo confused!!!

[tcampbell]

Just make it simple. That is why people do EI. EI is a range, no an exact. If a little over that is fine, it is better than a little under. 50% water changes weekly balance everything out

"Rule of Thumb"

Tank's (1)
20gal
50%H20 change-weekly
+/-1/4Tsp-KN03 3x a week
+/-1/16+Tsp-KH2P04 3x aweek
+/-1/16+Tsp K2S04 3x a week (optional)
+/-5ml Trace 3x a week CSM+B Plantex or other
+/-1-2ml Fe/Iron 3x a week (optional)

"If dosing a 10gal highlight C02 enriched tank, divide amount dosed each time in Half"
"If dosing a 30gal highlight C02 enriched tank, multiple amount dosed above by one and a Half (1 and 1/2)"
(math is simple this way)

Tank's (2)
40gal
50%H20 change-weekly
+/-1/2Tsp KN03 3x a week
+/-1/8Tsp KH2P04 3x a week
+/-1/8Tsp K2S04 3x a week (optional)
+/-10ml Trace 3x a week CSM+B Plantex or other
+/-2-4ml Fe/Iron 3x a week (optional)

"If dosing a 50gal highlight C02 enriched tank, multiple amount dosed above by one and a quarter (1 and 1/4)"

Tank's (3)
For a 60gal
50%H20 change-weekly
+/-3/4Tsp KN03 3x a week
+/-3/16Tsp KH2P04 3x a week
+/-1/4Tsp K2S04 3x a week (optional)
+/-15ml Trace 3x a week CSM+B Plantex or other
+/-4-8ml Fe/Iron 3x a week (optional)

"If dosing a 80gal highlight C02 enriched tank, multiple amount dosed above by one and a third (1 and 1/3)"

[|squee|]

What chemicals are you dosing? KNO3 and KH2PO4 only? Or with K2SO4 too?

If you are dosing only KNO3 and KH2PO4, you need not bother about the potassium, because Tom has calculated out that you do not need additional potassium other than what you get from KNO3 and KH2PO4. Read this.

If you have K2SO4 as well, don't fret you still can use it, read the post by tcampbell. Note the use of the word "optional"

Just follow Chuck's instructions and ignore Rex's ones, because you are dosing dry instead of dissolving them into a stock solution first. Also, the doses stated in the extract of the EI above all refer to dry dosing (those in "Tsp").

[barmby]

Since K do not cause algae. Why not, overdose K. Is there any side effect ?

[tcampbell]

Over dose of K will result in a need for extra N. The plants will respond by using up all the N quickly and thus having a shortage, which will cause plants to suffer, and thus algae to form.

[hypersushi]

Okay, thanks for the advice tcampbell and [squee]. I am assuming now that Chuck's calculator is based on pure mathematics and does not take into account plant uptake etc. Funny thing was, before I upgraded my lights to 3WPG, I was dosing 0.2 tsp of N and 1 tsp of K (I don't have P) and my plants were healthy except for some high ligh demanding plants. After 3WPG, I started getting BBA on the gravel.

My current dosing regime for my 4ft tank:
Sun - 1 cap of Ferropol (Trace)
Mon - 0.3 tsp N, 1 tsp K and 1tbsp Mg
Tues - 0.2 tsp iron powder
Wed - 0.3 tsp N, 1 tsp K
Fri - 1 cap Hagen Iron Enriched
Sat - 50% WC every two weeks (no dosing)

I guess I need to find a supplier of P then huh? I was warned that P will encourage existing algae to grow but it won't cause new algae.

[barmby]

I am not sure. There is a limit as to how much a tank of plants can absorb N. Hence, overdosing of K has no issue. Right ?

Over dose of K will result in a need for extra N. The plants will respond by using up all the N quickly and thus having a shortage, which will cause plants to suffer, and thus algae to form.

[PeterGwee]

Over dose of K will result in a need for extra N. The plants will respond by using up all the N quickly and thus having a shortage, which will cause plants to suffer, and thus algae to form.

Not true unless the amount of K was initially was limiting. Once the K is non-limiting, the amount of uptake for the rest of the nutrients would be up regulated which is fine if dosed enough (not lean...EI dosage figures are somewhat in slight excess).

Regards,
Peter Gwee

[juggler]

Since K do not cause algae. Why not, overdose K. Is there any side effect ?

See this topic "High K+ and very nice Ammannia" where someone overdose 100ppm or more of K.

I never tried it though, why waste?