Possible nute lock yellowing

Hey guys I'm doing dwc with Seedsman feminized seeds. My plant has been showing deficiencies which look like cal/mag/potassium/phosphorus. I'm a total newb this is my first grow so I could and most likely am wrong in my diagnosis . Here are some stats.

Temp: 75-79
Co2 ppm:800
Rh:60
Light: 600 Hortilux in a blockbuster 6 cooled with a 6inch valuline with a lumatek ballast.

Hydro rdwc bubble bucket a la Rumpleforeskin.4 sites filled with 3.5 gallons and a 5 gallon rez filled to 3.5 gallon. I use rodi water with 0 ppms. I add 7 ml of botonicare cal/mag plus then turn on my pump and mix. I then use the Lucas formula at 8 ml per gallon mix micro and finally16 ml per gallon flora.

Ventilation is controlled by a 6inch valuline exhaust on a cap 66 filter. Intake is a 4inch valuline. These along with the co2 are controlled by a CHHC 1.

My plants are 1.4 feet high and I was going to flip to 12/12 at 1.6 for a Target height of 4.5. I ran into a problem when my ballast took a dump and the clones where at full strength nutes and I had to switch from my 600 hps to 4 100 watt (26 actual) cfl on two plants and a 90 watt reef power compact light on the other 2. They all grew healthy even at full strength. I got my ballast back last Saturday so they been in veg for about 9 days.

I've noticed that the bottom leaves on all plants are showing yellow/brown spots like a phosphorus deficiency. New growth is showing yellow edges like a cal deficiency. Only one leaf on one plant is yellowing from the edges. It still shows green veins which indicates potassium I think. I checked for pests and cannot find any. I have doctor doom (sp) spray and fogger just in case.

I change nutes every 10 days. I last switched out on Thursday. When I mix I usually get a solution at 4.9 oh so I adjust. Well I put too much ph up and my ph went up to 6.0 so I used the ph down powder and got it to a ph of 5.5 where it is at now. I'm thinking I used too much ph up and down and that it may be causing nutrient lock. I am making rodi water now and am going to flush for half a day to a day. Is this ok? Do I have to throw that water out and them make new rodi and mix nutrients in? Here are some pics. Thanks in advance and feel free to ask about anything I may have missed. Happy growing!

 

Thanks I added more pictures. I definitely think the fluctuations also had a part in it. I usuqlly adjust to 5.5 and let it rise to 6.0 and then adjust. Il l try to keep it at 5.8

 

I should add the girls are white widows.

 

Just a update in case anyone stumbles upon this thread and has similar problems. OSUbuckeyes (thanks again) hit the nail right on the head. My plants werent liking the ph fluctuations at all. I adjusted ph daily and did a mild foiliar (sp?) Spray and they are as green as ever.