Adding nutrients back when topping up

Hello,

So far during veg I mixed up the nutes for the reservoir and only added ph'd water throughout the week. The EC stayed at the same level up until reservoir change.

Now when I switched to flowering I mix up the reservoir to EC 1.2, two days later I had to top off with water and when I did the EC went down to 0.9. Now if I keep doing this by the end of the week there will be no food in there.

So the question is should I add more nutes when I top off with water, and if so how much. I realize that there is no way to know how much of each element the plant consumes.

Do you guys add back nutes to bring the EC up to what it was or no?

Thanks.

Yes adding back nutes is necessary, i add back 25% of what i use to mix the res up to start with.
if it dont get my target ppm back i add a bit more at the same ratios

litterally the fourth thread from the top is the exact same question...

https://www.rollitup.org/hydroponics-aeroponics/530480-i-need-help-please.html

edit- I do give you points because your thread has a much better title than his.

johnny32 said:

Hello,

So far during veg I mixed up the nutes for the reservoir and only added ph'd water throughout the week. The EC stayed at the same level up until reservoir change.

Now when I switched to flowering I mix up the reservoir to EC 1.2, two days later I had to top off with water and when I did the EC went down to 0.9. Now if I keep doing this by the end of the week there will be no food in there.

So the question is should I add more nutes when I top off with water, and if so how much. I realize that there is no way to know how much of each element the plant consumes.

Do you guys add back nutes to bring the EC up to what it was or no?

Thanks.

Click to expand...

Adding nutrients back is no the way to go when topping off your reservoir, there is no way to know what has been used and what is contained in the reservoir.

Top of with plain water, your reservoir should be larg enough that you should not to need to top off that much to significatnly lower the EC.

You should be refreshing your reservoir from scratch every two weeks, don't trick yourself into to adding misc amounts of nutes. Trust me you will get it all wrong.

hellraizer30 said:

Yes adding back nutes is necessary, i add back 25% of what i use to mix the res up to start with.
if it dont get my target ppm back i add a bit more at the same ratios

Click to expand...

How do you know the concentrations of what is left in the reservoir, when do you have to strat topping back up your reservoir? eventually your reservoir nutrient levels will be far out of the required ratios.

regards,

jesburger said:

litterally the fourth thread from the top is the exact same question...

https://www.rollitup.org/hydroponics-aeroponics/530480-i-need-help-please.html

edit- I do give you points because your thread has a much better title than his.

Click to expand...

He was asking how often to change his water and nutes, and how long the nutes will last in that time. I know the nutes will deplete during the week, I was just wondering if it is more beneficial to add them back to keep the EC at a certain level or not. I've read multiple threads saying that adding back nutes is harmful because there is no way of knowing which elements the plants use out of the mix you put back in there.

My bad though should have stated I change the reservoir every week and that I wanted to know if adding nutes back while topping of with water during that time is more beneficial than harmful to the plants.

ru4r34l said:

Adding nutrients back is no the way to go when topping off your reservoir, there is no way to know what has been used and what is contained in the reservoir.

Top of with plain water, your reservoir should be larg enough that you should not to need to top off that much to significatnly lower the EC.

You should be refreshing your reservoir from scratch every two weeks, don't trick yourself into to adding misc amounts of nutes. Trust me you will get it all wrong.


How do you know the concentrations of what is left in the reservoir, when do you have to strat topping back up your reservoir? eventually your reservoir nutrient levels will be far out of the required ratios.

regards,

Click to expand...

For one i know my plants and what they need! At some point between the 2week time frame you will need to add back
water and nutes. Adding 25% of your normal mix at that ratio will get you as close as you can get without a lab. So
picture this target is 1050ppm after 4or5 days theres water loss ppm can either go up or down depending on how much
your plants need or maybe you mix it to high! Eitherway if it goes up then just add enough water to get back to your
target, if it goes down refill your res and add your nutes at the ratio you did to start but little bits till you reach your target.
this method will get you to 2weeks with out any def issues

johnny32 said:

He was asking how often to change his water and nutes, and how long the nutes will last in that time. I know the nutes will deplete during the week, I was just wondering if it is more beneficial to add them back to keep the EC at a certain level or not. I've read multiple threads saying that adding back nutes is harmful because there is no way of knowing which elements the plants use out of the mix you put back in there.

My bad though should have stated I change the reservoir every week and that I wanted to know if adding nutes back while topping of with water during that time is more beneficial than harmful to the plants.

Click to expand...

If your changing your res weekly or even bi-weekly then I would only top off with water.

hellraizer30 said:

For one i know my plants and what they need! At some point between the 2week time frame you will need to add back
water and nutes. Adding 25% of your normal mix at that ratio will get you as close as you can get without a lab. So
picture this target is 1050ppm after 4or5 days theres water loss ppm can either go up or down depending on how much
your plants need or maybe you mix it to high! Eitherway if it goes up then just add enough water to get back to your
target, if it goes down refill your res and add your nutes at the ratio you did to start but little bits till you reach your target.
this method will get you to 2weeks with out any def issues

Click to expand...

Whatever works for you go with it, I personally do not like dumping back more nutes in a unregulated manner.

You may have dialed in your reservoir replenishment to be comfortable with a 25% solution from your normal mix but your using more nutrients each top off without any sound basis of what the levels of micro/macro nutrients remain.

As plants uptake water they do not necessarily uptake nutrients at the same rate and as this occurs, the plants might be drinking lots of water but not eating much food. The result is that in a matter of hours, as the water is depleted, the concentration of the nutrients in the bucket can reach toxic levels. So it is critical to always under feed your plants in this system.

Click to expand...

regards,

I top off with water. take a ppm reading and then enter numbers into my phone. A buddy made a lucas app for my phone. So I punch in Current ppm. Target ppm. res. size and it tells me how much nutes to put in.. Awesome app..

budsMI said:

I top off with water. take a ppm reading and then enter numbers into my phone. A buddy made a lucas app for my phone. So I punch in Current ppm. Target ppm. res. size and it tells me how much nutes to put in.. Awesome app..

Click to expand...

How do you know exactly what has been used up in the reservoir? PPM's are a measure of total disolved solids (TDS) and determined by weighing.

A solution of nutrients dissolved in water at a strength of 700 ppm means that there are 700 milligrams of dissolved solids present for every liter of water. To accurately calculate total dissolved solids (TDS), one would evaporate a measured filtered sample to dryness, and weigh the residue. This type of measurement requires accurate liquid measurement, glassware, a drying oven, and a milligram balance.\

Example: 50 mL of the 700ppm solution would leave ~35 mg of salt at the bottom of a crucible after drying (what we need to know is the chemical makeup of the salt).

So you top of your water and figure that your PPM went from 800 PPM to 640 PPM, how much nutrients do you add back? how much N? or P? or K? if you don't know the MASS and/or concentration of each micro/macro nutrient left in the solution you also do not know what the plant has used.

What happens if you top off the soloution and the PPM's have gone up? Then what do you do?

Topping off with nutrients is guessing at best, depending on how long this is done your reservoir may be toxic beyound believe for some micro/macro nutrients.

regards,

Never a problem... My buddy has been running same system for years doin a perpetual. never ever a problem. best meds around!!

I have been using my method as have a bunch of friends and all is good to.

Thanks for the opinions guys, this is what I'll do: on one side I will top up with ph'd water and on the other side I will add nutrients back to bring the EC up to what it was and monitor the progress.

johnny32 said:

Thanks for the opinions guys, this is what I'll do: on one side I will top up with ph'd water and on the other side I will add nutrients back to bring the EC up to what it was and monitor the progress.

Click to expand...

report back in this thread with the results!!

I top off and add nutes. My plants are beyond healthy.

permat said:

I top off and add nutes. My plants are beyond healthy.

Click to expand...

and a little burnt from your posted pictures but nice setup and good recovery.

Topping off with nutrients is very hit and miss, if you can get a good ratio that does not hinder the plants than great but what I have seen is most people just guess what ratio of nutes to put back and end up doing more harm to the plants than good, that problem strikingly does not come up when topping off with plain water.

regards,