In regards to cool nights

How's it going everybody? This is my first actual post here but that doesn't mean I haven't had a lot of questions answered here already. Kudos to all the kind and knowledgeable growers here. Did some light searching and couldn't find anything on my current question so decided to make a new thread.
Being that this is my first post here's a lil info on the set-up(day 3 week 6 of 12/12):
-Plants are in a 4x4x8 sunhut
-22"x22"x7" (8 gal) botanicare tray with lid as my DWC reservoir, lid has holes for 5" net cups with hydroton. Started with 5 plants though only 3 are currently in the system now
-elemental 127 18w dual output air pump with two stones(runs 24hrs)
-400w hortilux plus a sunblaze 24(4, two foot t5 bulbs)
-4" hurricane fan with 4"x12" phresh filter
-hood is a 6" cooltube
-a few oscillating fans
-nutes are just the GH line, running the expert recirculating feed program;though I occasionally give them some calimagic. The only other non GH item is terpinator, just a 0-0-4 from potassium sulfate.
-PH is always between 5.5 and 6.0
-Don't have an EC meter but should be around 1,200 to 1,400 ppm

If I missed anything just ask. Now on to my question, kind of a two part-er. First part, at night my temps probably get down into the high 50's...I am noticing very minimal downward leaf curling just at the top of my plants. Wondering if it's just the air temp? Or perhaps my reservoir temp is getting a little cool as well?
The second question, to combat this I would love to use some armor-si (a 0-0-4 from potassium silicate) to increase the plants vigor and resistance to temperature. The only catch is that silica is a very potent PH up in my experience. Basically strong enough to put my PH around 10 I imagine, if I were to add it at the recommended rate. Would it be ok to just add enough PH down to level it out? Or is that just a dumb idea?

Any and all advice is greatly appreciated! Happy growing everyone!

P.S. Just checked my reservoir temp, light has been on an hour..It's at a chilly 64 Fahrenheit, deff think this is contributing to the issue....

i find they grow a little slower in veg if its cold
during flower they seem fine mid 50s is pretty normal for me during winter months when the lights are off, i notice some plants will show more colour when its cold
i do not use any nutrient heaters for my reservoirs i have no idea what the temp is when it feels cold i am happy
if anything i would think about cooling the solution during summer but being in the UK its not necessary as outside temps are rarely high

peace

I would say that cold res temps could definitely slow down the growth and cause a little limp in the leaves. My night air temps drop down to 64 all the time during winter, but I am a soil grower. Are the buckets sitting on a cold floor? One thing I do is elevate my plants using plant movers so they aren't sitting directly on my cold basement floor. In my veg tent I put down a layer of rigid foam insulation on the floor, which works well.

32-56 f i get P lockout

The reservoir is elevated by a few bricks. But being that the it is suspended in mid 50's air it is a little too cool I feel. Pretty much gonna go ahead and say this is the problem haha..anything you would recommend for cheap? Im at a current loss..thanks for the input!
Happy growing!

silicone is fine to use or they wouldn't sell it lol, of course its fine to use ph down once the silica has uped your ph, just do some research on it tho, ive read this a lot, that you should add it FIRST to your RO water, than cal-mag or whatever equivalence or such that your told to add first, than nutes and then additives.. just look out for cloudiness when you add it, as long as your water stays clear when you add it in, your fine.. if your water gets foggy or milky looking than the si is grabbing and dropping other elements in the res. which is why its recommended to add first.. (just info from personal research)

Awesome info, thanks man Ill look into it and see how it goes.
Happy growing!

no problem man, good luck!