We have used several different fertilizer injectors, but mostly Dosatron. I cannot give you a comparison, but do know that a good,fast,source of repair filters/parts,etc. is important. The Dosatron injectors have worked well for us. If the others you mention have good parts facilities, then they might work well too.

Hey thanks for the post. I'm going to be injecting sulfuric acid for pH control.

Just found this publication that details the different injectors. Try "greenhouse fertilizer acid control" search to get more specific info on types and amounts of acid to use.

Here is a link that might be useful: injector information

that's a great link for detailed info. Thanks.

I'm using a Dosmatic Minidos 1% for injection of 35% sulfuric acid (Qual battery acid) right now and it works perfectly. I'm actually using 2 in series (1 for acid, 1 for fertilizer) with a remote injection kit.

I've been very happy with their products. Support is quick and helpful and the units are cheaper than the Dosatrons (which I've never tried).