EI math - Have I missed something?

[gabriel.basso]

Hi there everyone,

For the last 2 months I've been studying and learning a lot with the forum threads about EI and since then many questions have been answered... but the more I learn, the more I realize I know nothing and more and more questions arise everyday. So, now I guess it's time to start asking!

I have a 70by40by45cm tank (126 liters/ 34 US Gal), Fluval 304 with a DIY spraybar output, Pressurized CO2 (Azoo difuser), 2 x 24W T5 HO (actually I've got 4 x 24w, but I'm using just half of the light) and I've just bought 2 Sunsun 3000L/h to improve water flow.

In order to start with EI, I followed the 20 Gal tank recipe on Ceg's article about dosing with dry salts. By the way, as always, great didactics there . Actually, before I praise the author (not for his knowledge but for his teaching habilities ), let me ask you guys to evaluate if I got the right picture of it.

As my tank is 34Gal (34/20), I rounded 1.7 up to 2. So, for the NPK solution (600 ml) I mixed:
4 1/2 ts of KNO3;
1 1/2 ts of KH2PO4;
12 ts of MgSO4.
50 ml per dose, 3x a week.

For the trace solution, I got a hydroponics trace mix which concentration levels, for a 40L/g solution, are:
Iron (EDTA) 1.81 mg/L
Copper (EDTA) 0.45 mg/L
Zinc (EDTA) 0.18 mg/L
Manganese (EDTA) 0.45 mg/L
Boron 0.45 mg/L
Molybdenum 0.9 mg/L
Nyckel 0.9 mg/L

As I noticed Fe levels were too high considering a 0.5 mg/L target, instead of mixing up 3g of the powder (for my 120 L tank) I divided this by 3,5 to achieve 0.52 mg/L Fe concentration. So I added 4/7 ts in a 200ml solution. 25ml per dose 2x a week. (I know that the excess of Fe wouldnt cause any problem to the system, but I got a little concerned about Cu levels, since I'm planning to keep some inverts on this tank).

Did I miss something? I'll wait for your comments!

tks a lot
Gabriel

 

[ceg4048]

Yep, nothing wrong with those numbers. It's really quite easy. The hard part is figuring out CO2 and how to get good flow and distribution in the tank. Keep the lighting low for the first few months, do large water changes 2X or even 3X per week and you should be fine.

Depending on your tap water, you may be able to lower the Epsom Salts. Don't be afraid to deviate from these numbers if your particular tank warrants it. These values are simply baseline numbers.

Cheers,

 

[gabriel.basso]

Ok Clive, good to know I'm on the right path... I'll do as you say: keep lights low, lots of wcs and concentrate on CO2 and flow. I've just bought 2 sunsun 3000 L/h... there's gonna be a lot of testing here to find out a perfect position for the pumps.. maybe 6000 L/h plus Fluval will be too much flow, but I'll give it a try.

Just a last question: with more WCs than the original schedule, 3x per week for instance... Do I keep dosing the same way? I mean, sunday thru thursday and rest friday and saturday... or should I dose every day since the ferts will be less concentrated?

cheers

 

[ceg4048]

Hi Gabriel,
Here's the deal; every time you do a water change then that you've effectively "reset" the schedule to Sunday. This is not really a big deal. If you're changing water 3X per week, what happens is that you wind up dosing NPK after adding water and then dosing traces the following day. The next day after trace becomes Sunday water change. It just becomes an alternating pattern of WC+NPK one day, traces the next day.

After 6-8 weeks you can reduce the WC to the normal 1X per week. The only downside is that you consume more powder, but they're certainly cheap enough so it isn't too big of a hit. Plants really love clean water. When you do the WC make sure you get your hands in there and shake detritus from the leaves (assuming you have stems and rosettes). Gently preen and rub the leaves between your finger, like a bird cleaning it's feathers, to dislodge the bio-film that builds up on the surface of the leaves, and siphon the debris away.

Cheers,

 

[gabriel.basso]

Got it Clive.
After your explanation it seems quite simple and obvious!
About the extra powder consuption during the first couple months... Guess I got ferts enough at least for the next 5 years! wont be a problem

Thank you again mate.