[mufcglen]

i run twin di out of the back of the van and want to make my system 2 man, i have spare pumps and controllers etc but as my tank is tap water thats pumped through the twin di tanks i want to split it into 2 separate controllable feeds not just split one line from one pump.
is it possible to do?

[richard groves]

Can't see why not.
Just put the twin di's after the tank but before you split the hose into two to two pumps , controllers and reels.
I'm sure I have read on here that it is preferable to have the pump before the di to prevent air locks but if you have good leak free fittings for the di vessels etc. ( and perhaps a non return valve ) I'm sure it will still work . Sound like you have most of the bits already so no harm in trying. 

[Don Kee]

Put your tap water through both D.I's and then into van tank

Van tank then has pure in it supplying both pumps and you don't have to carry both D.I's about all day

[mufcglen]

Thanks guys, yes I have all the bits just need to work out how to do it, I'd rather not fill from tap even though tank would be pure as I believe the faster running tap water burns through resin quicker than a pump in the van going through slower?
I did think put the pump after the Di bottles so its sucking it through instead, suppose it would put more strain on the pumps but sounds like only way to do it really?

[richard groves]

Put your tap water theough both D.I's and then into van tank

Van tank then has pure in it supllying both pumps and you don't have to carry both D.I's about all day

Is it not true then that running tap water more slowly through di e.g. by using a controller makes the resin last longer ?
What you are suggesting makes sense and is far simpler if practical, but I suppose it all depends on the op's tap tds 

[richard groves]

Thanks guys, yes I have all the bits just need to work out how to do it, I'd rather not fill from tap even though tank would be pure as I believe the faster running tap water burns through resin quicker than a pump in the van going through slower?
I did think put the pump after the Di bottles so its sucking it through instead, suppose it would put more strain on the pumps but sounds like only way to do it really?

Sorry, we replied at the same time but yeah I'm on the same page as you 
I'm unsure as to whether it puts more strain on the pump, I've always been lead to believe that di does not offer any resistance to water flow if placed before the pump so my logic suggests that is not the case. The bigger issue is leaks and air locks but you can address that with better leak free fittings.

[Don Kee]

Yep, you will run through resin a bit quicker (depending on TDS) but OP was asking what was the best way possible with the equip & method he was using
(And lets be honest, even if it costs you one more bag of resin a year, it's not a lot is it?It's not even £10 a month! Especially if you've now got another chap out with you, it'll work out to half of one days work he/she earns you a year...)

If we're going for practicality and best all round option, either get a storage tank with RO (you'll save money in the long run no matter what your tap TDS is) or buy two more D.I's and put them after your second pump

I've tried DI before pump and the pump struggled.

[Matt.]

I would just pick up another 2 di vessels and run 2 pumps through double di.

If u have 2 poles working off the same pump the guy with the lowest brush gets more water than the other guy