To be honest even if you have an Apex you are way better off getting the GHL Doser 2! it works out cheaper, you can control it from your smart phone, its has way more features and its smaller. Plus with the GHL PAB port built in you never know what the limits could be
For the hobbyist that understands the importance of quality and in buying quality means buying once (spend now save later) it really can not be beat!