Auto dosing daily - some advice please

[Katch]

I'm running a high tech 90 litre (Fluval Roma). Lighting is 2 x T5 @ 24 watts (I upgraded the stock T8 system). CO2 is pressurized and my drop checker is green @ lights on and limey green by gas off at the end of the day.

I don't manage to get to the tank more than about 2 times a week, so I am finding it hard to keep the nutrients in the tank at a high enough level. My sollution, I'm going to build a fertilizer reservoir and auto add it to the tank with a submersible pump and electric timer.

I will continue to do weekly 65% water changes.

My question is what to put in the fert sollution? I don't want to use 2 pumps and 2 reservoirs so I need to be able to dose allinone (don't want to have to dose PO4 separately).

Can I just work out what my tank would need if I was dosing EI and add it to the reservoir with ascorbic acid and potassium sorbate? The weekly total EI dose will then be added in 7 daily doses.

Comments suggestions and corrections?

 

[GillesF]

Why not use less light? Less light = slower growth = less work/dosing

 

[Katch]

I grow plants that don't respond well to low light and I like the high growth. The current lighting is only about 2wpg.

 

[madlan]

I dose with an automatic system, works great.

Here’s the mix I use: http://ukaps.org/forum/viewtopic.php?f= ... 10#p164347
Get yourself a peristaltic pump too, much more controllable than a submersible: http://www.williamson-shop.co.uk/aquado ... 5551-p.asp

 

[Katch]

Not enough spare cash to get a peristaltic pump and they are prone to failure.I have spare submersibles lying around and have seen good reliable results from them in other's setups (one guy has been using his without problems for over 2 years).

So let's say my setup has enough capacity for 10 days

90 Litre tank needs

4.2g KNO3 per week........... /7*10 = 6g
1.62g KH2PO4 per week...... /7*10 = 2.31g
10.5g MgSO4 per week........ /7*10 = 14.29g
0.74g Trace per week......... /7*10 = 1.06g

So I add:

KNO3 - 6g
KH2PO4 - 2.31g
MgSO4 - 14.29g
Trace- 1.06g
Ascorbic Acid - 1g
Potassium Sorbate - 0.4g

to my fert reservoir and refill every 10 days?

How does that look?

 

[Katch]

I've ordered my powders so I guess we'll find out. Would still appreciate someone with more expertise than me verifying my numbers.