Hard water or nutrients too strong?

Okae guys I noticed something today when I checked the DWC there are white water spots on the top of the reservoir does that show that the waters hard? I noticed it on the jugs. Ive been using the tap recently and I'm starting to think that was the mishap that ruined my last two grows... Right now I got a seedling that was started in dirt but I transferred it to the DWC n it's been there for about a week now and the roots are starting to poke out of the net pots they are super white but the leaves are showing discoloration similar to mag Deficiancy...the other four are clones and the don't look like they're doing so good...

DETAILS:
Res holds about 2 1/2 gals
ppm of the tap water before nurse are added: 298ppm's
Ph about 5.5-5.7
water temp 29*C
Only used 1 1/2teaspoon dynagro liquid bloom and 1teaspoon liquid protect
Cab temp: 87-89*F
DWC with droppers till roots come through.
Lights: 18/6

Let me know what you think I should fix and any experienced DWC growers have tips I would appreciate it! Thanks rollitup!

White is most likely salt buildup. Pretty normal at the water line. You should be using grow (veg) ferts at this stage and that protekt is very high ph and concentrated (1/4 tsp per gal rec last i remember). be cautious.

Also with the tap I noticed a lot of ph jumping... I did some research and other people have that same prob so should I change the water tonight?

I thought it was salt build up but it looks the same in the jug with no ferts in it just tap water...I'm gonna run to the store and get a couple gallons of water and change it in a few...

[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Okae I got purified water at the store which is r.o. so I tested fully and heres all the info...roots aren't coming out the bottoms of the cubes so I got the droppers on till the roots hang...


R.O. water [/FONT][FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]-ppm- 15[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]-ph 6.5[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]
[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Tap water[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Ppm-239[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Ph-8.1[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]
[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]My reservoir setup:[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]2gal[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]1/2 teaspoon dynagro liquid grow[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]1/4 teaspoon dynagro liquid protekt[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Ppm-154[/FONT]
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Ph-5.5

From everything I learned it seems near perfect for the DWC setup and I hope the plants bounce back soon I'm only gonna veg till they get to about 6 inches.

QUESTION: will having the droppers on till the lights go out hurt or slow root growth and should I just leave the net pots 1/2 up on the net pots or will the droppers help it?? Thanks for any answers...[/FONT]