Yellowing tips of new growth. Is this MAG deficiency?

I recently just typed a whole writeup on my setup and everything I was using and i keep getting errors and it didn't autosave. So, to summarize I have 18 autoflowering plants (9 EasyRyders, 7 Afghan Kush Ryder, and 2 lowlife varietys which are younger) in FFOF soil. RH is 45-50 and recently stopped humidifying room so it will be at around 30ish(tell me if that is too low if im wrong) for flowering since all have shown sex about 3 days ago on day 18. Temps are between 75-85 during the day and 65-70 at night. Am running a 20/4 cycle under 1000w hps(just switched from MH).
The problem is that I have been using ph adjusted tap water, which after purchasing some test strips was found to be very hard water. I think this is causing some sort of deficiency from mineral buildup in the soil. Possibly magnesium deficiency. Is my thinking right? Anyone seen something similar that has some suggestions? I have allready started watering with reverse osmosis water. Should I add something to the soil or supplement with something else? Any help would be appreciated. They are all healthy besides the very tips of the newest growth as shown in the pics:
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I cannot see the pics but it is likely nute burn. You have them in FFOF...did you add any perlite and have you fed them additional nutes? If no perlite and yes nutes, or even 1 or the other, that is the issue. FFOF is very hot soil and has more than enough nutes for several weeks. If you did not add perlite you may want to get some, make a fresh batch 3:1 ratio and repot. Or at least give them a flush. Best of luck and instead of copy/paste pics use the add pics tool in the tool bar, it is the one that looks like a pic of a tree in the link bar.

I actually started the seeds in FFOF mixed with 25% perlite, and have not used any nutrients as of yet. They have actually looked very green and healthy up until now, and I havn't changed anything from the begginning. Until just a few days ago they came up lush and green with no real issues. This is why I think it may be a lockout issue due to using hard water and building up salts/minerals for 3 weeks until my recent switch to reverse osmosis water.

Just curious, does the "like" mean you agree with my prognosis or do you like what Im doing? Either way I appreciate it. Thanks

Edit: At second glance this looks like maybe a calcium deficiency and not at all magnesium. What does anyone think?

ph buddy, if your using just water its your ph. got me a ph pen and no more yellow tips.

Well, I had been adjusting the water to about 6.8 with growth seeming very good. Then it seemed that right when they went into flower that the yellow tips started occuring. It seems like the bigger leaves that originally had yellow on them are growing out of it and the yellowing has diminished so Im really not sure what to make of it. Mostly people say it's nute burn, which would make sense if I fed them any nutes. Could it not be lockout or deficiency? I would love to get to the bottom of this, but the more I read, the more it seems like it could be a number of different things. I just really thought that my hard water supply might be contributing to lockout. The ph of the water was fine when adjusted, but that did not change the general hardness of the water. From what I have read, minerals can possibly build up and cause all kinds of deficits. I also saw on another forum someone said that it just happens sometimes when flowering starts. Im not sure I believe that as much as I would like to! No nutes, just plain tap water with good PH, temps decent, humidity just lowered to 35% from 50%, 1000w hps about 24" from tallest plant. Confused me.

The like was for the pics and the generally healthy look of the grow. You have obviously taken the successful growing by learning suggestion, you seem quite knowledgeable. So I am sure I do not have to mention that FFOF is a very hot soil and has a bunch of nutes in it from the bag. You seem to have a decent amount of perlite to buffer, but you may want to flush them a bit. Best of Luck! The +rep was for educating yourself before beginning this wonderful hobby!

I'm going to go with Nute Lockout. My plants looked very similar to this at a point. The whole time it was just my PPM (tds) was out of wack. if your water is too hard, then salt will build up and if you keep feeding it the same water then you're just adding to the problem. if your Ph and PPM are not in place, then your plants will have a hard time absorbing what they need to be healthy.

bkbbudz said:

The like was for the pics and the generally healthy look of the grow. You have obviously taken the successful growing by learning suggestion, you seem quite knowledgeable. So I am sure I do not have to mention that FFOF is a very hot soil and has a bunch of nutes in it from the bag. You seem to have a decent amount of perlite to buffer, but you may want to flush them a bit. Best of Luck! The +rep was for educating yourself before beginning this wonderful hobby!

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Thank you, yes I have read quite a bit and wanted to have all the bases covered before begginning. To me it is possible to do things right the first time if you put enough into it. So you think I should flush them? I have read about this as well, but kind of scared to drown my plants, and have found arguments for and against flushing. Kind of just want to continue watering with my new RO water and see if it helps, but maybe I will get brave and flush. Thanks again for the rep!

Mr.Buds said:

I'm going to go with Nute Lockout. My plants looked very similar to this at a point. The whole time it was just my PPM (tds) was out of wack. if your water is too hard, then salt will build up and if you keep feeding it the same water then you're just adding to the problem. if your Ph and PPM are not in place, then your plants will have a hard time absorbing what they need to be healthy.

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So, you think my switch to RO water was a good idea then I assume? Did you switch your water source after this problem? If so, did this correct the problem, and in what timeframe? Anything else you did to correct the issue? Your input is appreciated. Thank you.

i have the same problem now!

last month, when i found my plants get sick i get a new RO system,and i changed the bigger pots,but since last week i feed them 20-20-20 foods,they were growing well few days,but the problem still showing up now,

what i gonna do?flushing or feed?

what are your ppm and ph?

mine was doing that they was just hungry i guess they clrared up after feed