try balancing to 6,8 to start, if the drift is constantly downward. nothing much you can do with an unbuffered product.
mother fucker.. wrote out an awesome response, now you get the slimmed down, angry version because of fucking GD spam filter. pls note the tone is due to frustration of the web site.
AN nutes suck a dick. they aren't ph-buffered products and claim to be "hydro" nutes, which is objectively stupid and incompetent. AN is a bunch of water-weight and needlessly splits nutrients into 10 different frickin bottles for no rason other than profit margin. the only molecule that can cause a precipitate is Ca++ and not typically at any concentration of common sense feeding dosage. 3-4 products that provide a well-balanced feed and ph-buffered is all you need to effectively adjust the formula until it works flawlessly in you environment. I was less aggressive toward AN in the first post, but ffs, frustration brought it out.. but it's stilll incontrovertibly true, too.
jr peters, southern ag, cropsalts, et al often have a "pro" line or "hydro" line of nutes. they are dry and need to be mixed into solution - most cost effective option. some are much cheaper than others. there is no reason to overpay for ubiquitous commodities, which the components of fertilizers are. for example, i pay about 100 usd every 4 years growing 30-35 plants a year. i grow fewer plants now but waste more water with a automated system and more frequent irrigations.. still lasts 4 years. Some spend that on fertilizer for 1 grow or even less than one grow. that is insanity.
find a 3-4 part system that is properly manufactured and buffered. i do not take care of my reservoir beyond darkness and well oxygenated / agitated/ room temp or better at all times. i never have pH swings. i refill at 50% and don't clean the bastard for an entire grow if i don't see anything slimy building up, lol.... not the best SOP and zero pH swings. that's what you get from a professional hydro nutrient lineup.