Water pumps come into play when you are recirculating your nutrients RDWC vs DWC. Typically you would add an additional tote to your system and then link all 3 together.
Or
Running a pump sprayer for cloning
How much build up are we talking and what are your water temps? Also, are you giving it time to dissolve and mix when adding nutes?
I run an overpowered fountain bubbler combination in my reservoir just while adding nutes to help mix everything up, perhaps add some additional oxygen in the system, and warm my water up some before it hits the roots. I have found some nutes do not mix well at all so I’ll dump back and forth between 2 gallon jugs and let sit for 30 minutes before pouring. All of those changes helped me but it all comes down to one question, how are your plants?
If you are using products like Armor or Cal mag you are directed to add those to the nutrient solution first. If not; then the salts in your nutrients will coalesce and sink to the bottom and will look like sand.
If you have an ‘off’ smell to the rez or it’s slimy you have developed root rot. Are you running any beneficial microbes like Hydroguard? Do you do a rez change? If so; how often?
Personally I would be investing in a chiller to ward off any issues with pythium and you gain the advantage of additional O dissolved in the colder water. I would be very surprised if your nutrients are under 70F in your grow space.
I would like to know:
How old are plants? And how many?
What EXACTLY are you using for light?
What is the PH and TDS of your nutrient solution?
What EXACTLY additives are you using? Just the base nutes or the full Monty?
What is your light schedule?
What are your ambient temps?
The plants are fine. I just noticed today there was buildup nothing that’s horrible but I just noticed it. My plan was to switch out the totes every 10 to 14 days with fresh nutes and water depending on the qualityat that time. With 1 day of fresh ph water then adding nutrients the next day. The next switch is tomorrow with all new water and dumping the current totes out. My ph is 6.2 in both and 892 ppm in both give or take. I’m in the third week of 12/12. All other reading are fine and my temp is pretty constant at 62 degrees. Nutes eight now are calmag,open sesame, tiger bloom, big bloom ( whichever is the orgnic one, I’m not on site at the moment ) @Tegridy @Myfriendis410
62 is awesome if you can sustain it. I have my res & airlines pumping from my basement with every bucket and line double insulated and can still only hold 64 w/o a chiller. Post pics/info on how you’re keeping it cool if you don’t mind. I’m starting a simple DWC veg tent this week and might snag some ideas.
@Myfriendis410 is on the money with Armor and Calmag. They tend to bind and difficult to mix but your plant will be the first to tell you when its happening because your PH will be all over the place.
How about a picture in natural light?
I can’t do a natural light pic due to how I’m set up. I’m transitioning at the moment from soil to DWC. Maybe when I change tanks or something. All DWC are clones and soil are mostly clones also. I was about to dump all of my plants but instead I and trying dwc setup. I got tired of the bugs that come with soil. I tried to send a pic but not sure if it went through
My two cents fwiw, I do single bucket DWC 5 gallon buckets. After using different kind configurations, I settled on a 950gph air pump. It splits six ways, connected to three airstones - the huge 4" x 2" cylinders per bucket it really churns the water and nutrients. Plants reflected changes right away. Helps allot when your root ball grows huge 
you want all the air you can pumping in the bucket. Your setup liquid volume wise - I would use at least 6 big cylinder stones. Any questions give me a holler. Save you upgrade grief 
just harvested this
nice @neofirebird just add more stones to churn was another option. I have a 6 way also big dont know the actual readings. thanks 4 the advice
Like 20. For 2 two packs Amazon