Wow, I haven't seen this products from Ikea. Will check it on our local store next weekend.

About improvement:

1. It's likely that you got rootroot because of insufficient amount of oxygen in water. According to the structure of this grower, you either used not enought amount of stones, or you have distributed them unevenly. And also, 15min of aeration every 1,5 hours isn't enough for any DWC-like setup. Increase it at least to 15 min every 30 min.
2. Change your pump to the noiseless one - I usually recommend Tetra products, they are reliable and powerful. In general, they justify their price: https://www.amazon.com/Tetra-Whisper-Easy-Aquariums-Non-UL/dp/B0009YF4FI/ref=sr_1_6?ie=UTF8&qid=1529841047&sr=8-6&keywords=silent+aquarium++air+pump
3. About light - it's better to switch to specialized agronomic light. They will be more effective, but will give violet light:

https://www.amazon.com/RAYWAY-11-5inch-Greenhouse-Hydroponics-Vegetable/dp/B06XPGNLCW/ref=sr_1_13?ie=UTF8&qid=1529841312&sr=8-13&keywords=grow+led+strip

https://www.amazon.com/dp/B01IVQ96KY/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B01IVQ96KY&pd_rd_wg=uu64E&pd_rd_r=DT9YC0VHFAN5VCWHNA05&pd_rd_w=nFiJN

I've found the one with yellow-light, but I don't know, is it good for plants (they don't provide adequate spectre info): https://www.amazon.com/Roleadro-Upgrade-Developed-Spectrum-Generation/dp/B01HI3AFYM/ref=pd_sim_86_12?_encoding=UTF8&pd_rd_i=B01HI3AFYM&pd_rd_r=69G0G3YSD1DN5NCPFQZD&pd_rd_w=k0I8Q&pd_rd_wg=RZTJ2&psc=1&refRID=69G0G3YSD1DN5NCPFQZD

Feel free to ask any questions!

How many square feet can you fit those tubes into?

E: I ask because this one is my favorite of "the cheap ones" but if you need to cover a lot of area with really high lumens, it's not going to be enough. But if you can cram them into a few square feet you should be able to cover them with two of these.

Again, it's not one of the real professional solutions, but of the cheapo lights, it's one of the best ones.

https://www.amazon.com/Roleadro-Hydroponic-Greenhouse-Succulents-Seedlings/dp/B01IVQ96KY/ref=mp_s_a_1_16?ie=UTF8&qid=1533050229&sr=8-16&pi=AC_SX236_SY340_FMwebp_QL65