First DWC grow. Questions about nutes

I have a 30 gallon tub with six plants. There are 25 gallons in it currently bringing the water level up to the bottom of the rockwool. I went by the directions on the bottles and used 125 ml of GH Flora Micro, Gro, and bloom. It seemed like alot of nutes to me. Is this right? If not what would be the ideal nute mix? also how often should I change the water?

I personally am JUST about to start my first non soil grow and from what I have researched...you will never quite know for sure without an EDS (is this correct?) meter. Basically it measures your parts per million of nutrients...it gives you an idea of the strength. And if these little plants of yours are just poking through the rockwool...you might want to keep that ppm at around 200, if anything. But hey, im tellin you this is just from what i have read so far. But yeah to get a better answer to your question you will need to supply more info. Like...how old are the plants?

Deuces

The plants are a week old 5 of them are about 2 to 3 inches tall and one is very small.

ye, get an EC meter.
the "Blue Trechon" meter is very good and robust.

I'll save you some money ...

Eliminate the "Grow." You don't need it. That's the green bottle.

For vegging: 5ml Micro. 10ml Bloom.
For Flowering: 8ml Micro. 16ml Bloom.

Those are ml per gallon of water.

Vi