Yellow, brown spots on older leaves, seems to be spreading to newer leaves

Im new growing so please bare with me. My plants first seem like there just turning yellow, but over time they seem like there getting brown spots. On my biggest plant i got brown spots at the tip and my second biggest seem like there in middle of the leaf. i dont know what ph levels are and not sure if that even has anything to do wit it.

Well the soil im using is miracle grow, i got it for free. They were doing completely fine till now. I water once a day with faucet water. I read somewhere it might be nitrogen so i use a nitrogen fertizizer slow release yesterday. Not sure if its helping yet tho, i mean it is slow release. some leaves even got a bit of black on them. im also growing in a pc grow box. im using 3 100 watt lights, i believe there call cfl not positive. the temp is usually about 75-80 degrees, depending on the time of day. i look at them earlier and i saw a red bug on a stem of a leaf. but i went to grab and it flew away. i examine plants but i dont see any bugs. but then again im a little inexperience. If ya think it is bugs what do ya recommend. im sorta broke, so is there any household product that i can make or use. here some pics, hopefully its not bugs. Please help asap. Also there about 3 weeks old.

Sorry you never got a responce. Im having the same exact problem.

could be a ph problem... knowing the pH of soil is huge since there are specific ranges that nutes grow in best here check this out......sorry its geared towards soil less mix which I use.....
[FONT=&quot]Hydro and Soil less Mediums[/FONT][FONT=&quot]
Nitrogen gets locked out of Hydro, Soil less mediums at the levels of 4.5-5.0.
Nitrogen has the best absorption rate at a ph of 5.5 to 8.0
(Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range to have Nitrogen is: 5.0-7.0. Anything out of that range will contribute to a nitrogen def.[/FONT]
[FONT=&quot]Phosphorus gets locked out of Hydro and Soil less Mediums at ph levels of 6.0-8.5.
Phosphorus is absorbed best in Hydro and Soil less Mediums at ph levels of 4.0- 5.8. (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a Phosphorus Deficiency.[/FONT]
[FONT=&quot]Potassium gets locked out of Hydro and Soil less Mediums at ph levels of 4.0-4.5, 6.0-6.5.
Potassium is absorbed best in Hydro and Soil less Mediums at ph levels of 4.7-5.3, 6.7-8.5. (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a potassium deficiency.[/FONT]
[FONT=&quot]Magnesium gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-5.7
Magnesium is absorbed best in Hydro and Soil less Mediums at ph levels of 5.8-9.1
(Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a Magnesium deficiency.[/FONT]
[FONT=&quot]Calcium gets locked out of Hydro and Soil less Mediums at ph levels of 2.0- 5.3
Calcium is absorbed best in Hydro and Soil less Mediums at ph levels of 5.4-5.8 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a Calcium Deficiency.[/FONT]
[FONT=&quot]Zinc gets locked out of Hydro and Soil less Mediums at ph levels of 5.7-8.5
Zinc is absorbed best in Hydro and Soil less Mediums at ph levels of 4.0-5.5 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a Zinc Deficiency.[/FONT]
[FONT=&quot]Iron gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-3.5
Iron is absorbed best in Hydro and Soil less Mediums at ph levels of 4.0- 6.0 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to an iron deficiency.[/FONT]
[FONT=&quot]Sulfur gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-5.5
Sulfur is absorbed best in Hydro and Soil less Mediums at ph levels of 6.0- 9.5 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to an Sulfur deficiency.[/FONT]
[FONT=&quot]Manganese gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-4.5
Manganese is absorbed best in Hydro and Soil less Mediums at ph levels of 5.0-5.6 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a manganese deficiency.[/FONT]
[FONT=&quot]Boron gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-5.0
Boron is absorbed best in Hydro and Soil less Mediums at ph levels of 5.0-6.0(Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a boron deficiency.[/FONT]
[FONT=&quot]Copper gets locked out of Hydro and Soil less Mediums at ph levels of 6.5-9.0
Copper is absorbed best in Hydro and Soil less Mediums at ph levels of 2.0-6.0 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a copper deficiency.[/FONT]
[FONT=&quot]Here are some ph buffers when your ph is too high: Use these SOIL PH Adjustments to lower your ph: sawdust, composted leaves, wood chips, cottonseed meal, leaf mold and peat moss. Sawdust, composted leaves, woodchips and, lemon juice, PH DOWN.[/FONT][FONT=&quot]

Hydro PH Adjustments: PH Down (vinegar and lemon juices are good for soil, but not recommended for hydro use) Phosphoric acid during flowering and Nitric acid for vegtative growth.Thanks goes out to syko2 for that one! (Only quality PH buffers should be used to adjust ph and be sure the buffer and nutrient work's well together.)

Here are some that will raise the ph: use these SOIL Adjustments when your ph is to low: PH UP, dolomite lime, hardwood ash, bone meal, crushed marble, or crushed oyster shells, potassium hydroxide <--- Thank you Uncle Ben!

Hydro Adjustments: PH UP,lime,potassium hydroxide and potassium sillicate .(Only quality PH buffers should be used to adjust ph and be sure the buffer and nutrient work's well together.)[/FONT]

I had the same problems with my two of mine I am growing I am using miralce grow moisture control and mine are about 3 weeks old to 2 of my 4 plants got brown spots but since I transplanted them into a larger pot (I had mine in party size cups to start out) the brown spots quit appearing.... also I went froma 21-7-14 NPK to my new soil Sea Green with a NPK of 10-8-6. I used half miralce grow half sea green and am supplementing them with veggin food with a 24-8-16 NPK. Is the Miracle grow your using include 3 weeks of nuts in the soil?

pH is blocking nutrients

mg already has all the nutes your plants will need for vegging I use to always try to boost up my yield by adding nutes and you end up burning your plant which slows its growth down twice as fast as it would if it was just a def. You should not add any nutes untill the bottom leaves show their first signs of yellowing then add 1/4 the recommended ammount at first slowley increasing to 1/2 the recommended dose. Only feeding every other watering. Mj needs very little nutes campaired to other veggies/fruits/herbs thats why specialized nutes for mj have very low npk values. MJ really likes a even npk value during vegging and higher p during flower. Its looks to be a little over fertilized and you never should need to water everyday. With time realese nutes and nutrieized soil you fertilize everytime you water. That might be why the other guys problem kinda went away when he switched to a larger contanier because he had to water less. Only water when the top 1/8 to 1/4in of the contanier is dry usually every otherday for small pots and every 2-3 days for 3-5 gal pots depending on temps... Also I was never a fan of time releases nutes because once you add them its near impossible to stop their delivery if or when you need.. IMO i would remove as much time release nutes as possible and flush the plant with plain water min. 3 times the volume of the contanier. I also recommend getting a very inexpensive ph tester for fish tanks prob under 10$ test the water and adjust the ph like lonley said he hit the nail on the head with that. Also increase the contanier size min. 1 gal for every foot you want your plant. If .youwant larger/better yield get a larger contanier more powerful light more co2 and more air to the roots. Not more nute..or atleast in my experience. PS constant soaking soil sufficates roots,

im about a Month in growing now (hydro).. just started using maxi grow on my plants.. they LOVED it.. but now.. some brow spots came.. i also started using cal-mag same time as the maxi .. the temp has been the same since birth75-80.. so idk if thats a problem.. am I using TOO MUCH nuts.. should i tend to it MORE FREQUENTLY now that its growin bigger... PLZ PLZ HELP.. im confused... but i KNO i can fix this.. my BABIESS =[

I had a similar problem that seems to have gone away once i flushed, lowered my nutes a bit, transplanted to a half coco/ half soil mix with good airation and stopped watering so much. When i did water / feed i added lime juice to lower the PH i also used topmax which has humic acid to help nutrients get aborbed. there is no reason you should be watering every day in soil with a plant that young. If you don't have nutes get some. it could easily be a deficiency although i think its more likely a combination of overwatering / PH. also, miracle grow burns alot of young plants. try to get her into something good and feed her yourself so you can controll it instead of hoping the miracle grow has the right balance, because chances are, it doesnt. good luck brother.