Add fertilizer to my rain collected deposit?

[Fidur]

So, I always use a 500 lt. water deposit just to water my bonsai. This deposit usually contains collected rain water, but I refill when needed with a RO system. It will always be used only to water my bonsai. It has an automatic pump to add pressure to the hose.
I usually use liquid fertilizer that I mix in the watering can before watering.
I've always wondered if I could simply add the fertilizer directly in the deposit, but I refrained, as there may be colateral effects (deposit contamination, pump problems,......)
Now, what do you think would really happen (long term) if I add the fertilizer in the deposit in the appropiate moments of the year?

 

[19Mateo83]

I think it would be hard to keep the concentration consistent unless you know exactly how much you are using at a time…unless you use the entire 500L at each watering. You could always add an inline mixer after your pump so you don’t have any issues with concentration or mineralization.
Something like this would work for granular fertilizers. They also make something similar for liquid ones as well.

Amazon.com

 

[Wires_Guy_wires]

I wouldn't pre mix it. From all the things I read from people who pre mix, it's a huge challenge to get everything right, and especially to keep it right.

Nutrients can precipitate and evaporate and you don't want that, because it will destabilize the concentrations.

 

[WNC Bonsai]

You’d be better off to add an automatic doser system to your watering hose. That way you wouldn’t need to worry about the concentrations in your deposit fluctuating. There is a recent thread on here about such systems. Also check out Harry Harrington's recent YouTube videos about switching to rainwater.

 

[shohin_branches]

That's a good way to clog up your system and fill it with algae

 

[Shibui]

Algae seems to be the big problem. Add nutrients to water, leave it sit for a few weeks and the water suddenly turns green - or brown.

 

[penumbra]

If it is in strong light, you will get algae regardless of whether you use fertilizer or not. Next year I will cover my 275 gallon tank to block the light.

 

[Paradox]

I agree with the comments above that it's best to not pre mix in a barrel. Only mix what you are going to use in one watering session. Plus watering with fertilizer every time you water might be too much fertilizer

 

[leatherback]

A friend of mine has a waterbutt partially filled with dung. THe rest is water. Uses that to water once a week. Stinks but does the job. The other days they water with a "clean" watersource, if I understood correctly.

 

[penumbra]

For the record, when I use my 275 gallon rain collector (holds about 225 -250 gallons) I most often use it with fertilizer. Sometimes I use Miracle Grow, sometime Miracid, sometimes Neptune's Fish with Kelp. I mix it up just prior to use and use it all at one time.