Many questions about hydroponics!

[Davephan]

I just received my hydroponic fertilizer in the mail. I plan to do the MHPGardener mix of Masterblend 4-18-38, plus calcium nitrate and magnesium sulfate. I don't have a way to measure pH yet. I plan to buy a pH testing meter and testing strips.

I was wondering how critical pH is for hydroponic gardening. If I just took tap water, let it sit overnight or a couple days, then attempted to use the water without testing the pH, would the results be significantly worse than if I waited until I purchase a method to test the pH.

How much of a difference does adjusting pH make? Is it a huge difference? Or a minor difference? I'm guessing it depends on how far off the pH to the ideal range. I understand the recommended range for tomatoes and peppers is 6.4 to 6.7.

Another question. Is there a difference between the taste of hydroponically grown produce verses soil grown produce? I've experienced a huge improvement in taste from my soil grown tomatoes and peppers, compared to the grocery store tomatoes and peppers.

[GpsFrontier]

Hello Davephan,

I don't have a way to measure pH yet. I plan to buy a pH testing meter and testing strips.

Personally I wouldn't waste money on a pH meter or pH litmus strips. Even good electric meters can give false results even when taken care of and calibrated properly, and good ones are expensive. litmus strips tend to be to hard to get a good accurate reading. I'd recommend using pH drops. Their similar to litmus strips in that you read the color, but the drops will give you a much more accurate color reading. Even if you do choose to spend the money for a electric ph meter, make sure to get some pH drops to double check the readings if there is any question of it's accuracy. I wrote this: pH test kits versus electronic pH test meters about it.

I was wondering how critical pH is for hydroponic gardening.

pH is very important, it's the difference between healthy plants and plants with deficiency. Plants are only able to absorb certain nutrients when the pH is within a specific range. When the pH is out of range, the plants cant absorb the nutrients in the nutrient solution no mater how perfectly balanced or concentrated it is. When the plants can't absorb the nutrients, they begin to suffer deficiency.

If I just took tap water, let it sit overnight or a couple days, then attempted to use the water without testing the pH, would the results be significantly worse than if I waited until I purchase a method to test the pH.

There are two parts to this question. First, naturally it depends on how far off the pH is, and how long you wait. A few days, a week, I wouldn't worry about it, multiple weeks I would wait till I was able to test pH. However if the pH is real high, it wont mater when you adjust the pH, the damage to the nutrient solution will already be done. When the pH reaches above 7.0 and higher calcium and iron molecules/ions will bond, when they do, both calcium and iron that have bonded will be unusable to the plant. This bonding cant be undone, even if you lower the pH to the right range.

Second, using tap water may be a problem as well. Most water supply's are high in some dissolved minerals like calcium, manganese, iron etc. etc. These excess minerals through off the balance of your nutrient solution. And Again here when calcium and iron concentrations are high they want to bond together, even when the pH is in the right range. Sometimes this iron and calcium bonding is refereed to as "fall out" or "precipitation."

How much of a difference does adjusting pH make? Is it a huge difference? Or a minor difference? I'm guessing it depends on how far off the pH to the ideal range.

Yes, that would absolutely depends on how far off the pH is. The farther out of range it gets, the less the plant is able to absorb the nutrients. 0.5 out of range not that bad, 1.0 or more out of range not good. Above 7.0 not good, unless it's a specific plant that does OK between 7.0 and 7.5 like some hot peppers. But in general you never want the pH to go above 7.0 because iron and calcium will tend to bond.

I understand the recommended range for tomatoes and peppers is 6.4 to 6.7.

Not only is that range a bit to small, it's on the high side. Tomatoes 5.5-6.5, Peppers 5.8- 6.5. In short both will do well around 6.0. Almost all hydroponically grown plants do great around 6.0. For Hot peppers you can increase the heat by increasing the pH, but if you have other plants in the same system the other plants will suffer.

Is there a difference between the taste of hydroponically grown produce verses soil grown produce? I've experienced a huge improvement in taste from my soil grown tomatoes and peppers, compared to the grocery store tomatoes and peppers.

Ah, the debate question. The real answer is that depends on you. It depends on how well you take care of your plants, the nutrients you provide them, whether you bother to check pH and how often, environmental factors and stress, in short the attention you pay to your plants. Flavor depends on whether the plants get the nutrients they need, and if the plants are stress free and healthy. You have a lot more control over the plants environment, nutrients, and thus stress levels when you grow them hydroponically than if they were grown in soil. It's up to you whether you do or not, and how well you take advantage of it or not that will determine flavor.

As for the difference in taste between tomato's you grew in soil yourself and what you buy at the store. That has to do with shelf life. You need to remember store bought produce is picked early before it's actually ripe and had a chance to develop it's full flavor. That's done to prolong it's shelf life. The stores cant sell soft, bruised, or moldy fruit, so they need them to last as long as they can before they get soft so they will sell before they have to through them away. Ripe tomatoes will get soft in 1-2 days, and peppers not much longer. When you pick your tomato's and peppers at home you don't pick them before their ripe and place them on the counter or in the fridge, then wait a week or two to eat them I'm betting. You pick them when their ripe and eat or use them within a day or two. That's why there's such a big difference in taste between what you buy at the store and grow yourself.

I mean think about it, everybody is guilty of it, including me. When you go to buy tomatoes (any produce) at the store you feel them to make sure their firm and not soft or bruised right. The reason their firm is because their not ripe. But if their soft you know they wont last long and seem like their even rotting, so you choose the firm ones. When you pick them at home they are softer than the ones you buy at the store, but you know their fresh, and your going to use them right away anyhow. They taste much better because you let them actually ripen before you picked them. If the store did that they would have to throw them away by the time they got to the store. Just the bulk weight alone would squash the ones on the bottom of the pile right away. All that would be left by the time they got to the store is tomato sauce. But we are all so used to the bland tasting produce we buy from the store, that's it just seems amazing when you taste home grown produce. Night and day.

[Davephan]

Thanks for the advice! I will buy the pH testing drops, plus pH up and down.

I plan to start off with tap city water and let it sit for a day or two. I assume that letting it sit before using it will improve the water for growing plants. At what point in time to I measure the pH and adjust the pH? I'm not sure if there is a optimum time to let the water sit before using it. Would filtered water from my refrigerator or using a filtered water pitcher like Brita or Zero Water be better than using city tap water?

After the pH is tested, adjusted, and re-tested, the hydroponic fertilizer is added. Does the pH need to be measured again, and the pH re-adjusted again? Does adding the fertilizer change the pH. After the nutrient mix is created, how often does the pH need to be retested and re-adjusted?

Is there a way I can determine when to add more nutrient as the plants consume the nutrients? I assume there is a way to test for the nutrient concentration.

About how long would the nutrient last before throwing out the mix and starting with a new batch?

[GpsFrontier]

Hello Davephan,

I plan to start off with tap city water and let it sit for a day or two. I assume that letting it sit before using it will improve the water for growing plants.

No, not at all. The only thing letting the water sit does is allows any chlorine in the water to dissipate. The excess mineral salts will continue to remain in the water forever. Even if you let it sit so long half of it evaporated, all that would happen is the excess mineral salts would become twice as concentrated because you cut the water volume in half.

At what point in time to I measure the pH and adjust the pH?

It's best to check and adjust the pH before and after you add the nutrients. As a new grower, you should check the pH every day. As you gain experience you will begin to understand how and why the pH fluctuates or changes. Eventually you will be able to predict pH changes and you wont need to check pH every day. You should adjust the pH anytime it's out of range.

I'm not sure if there is a optimum time to let the water sit before using it.

The chlorine should dissipate in a day or two, it will dissipate quicker if you use a air pump and air stone to aerate and circulate it. If you cant smell the chlorine anymore, it's likely all dissipated.

Would filtered water from my refrigerator or using a filtered water pitcher like Brita or Zero Water be better than using city tap water?

Absolutely, as for your refrigerator water, that depends on the quality and how often you change your refrigerator water filter. Often people use a inline filter, but the refrigerator often has one inside as well. Most of the time people forget to change the one inside, and the inline filter is behind the fridge so nobody even sees it to change it.

As for Britta and Zero water, again much better than tap water. and most likely even better than the refrigerator water. Zero water would be the better than Britta because it has a 5 stage filter that includes a ion filters needed to take out dissolved solids. Britta just uses carbon filters, and you need ion filters to take out dissolved solids.

After the pH is tested, adjusted, and re-tested, the hydroponic fertilizer is added. Does the pH need to be measured again, and the pH re-adjusted again?

As I mentioned earlier as a new grower you should check pH daily until you understand how and why pH changes and fluctuates. Over time you will begin to be able to predict when and why the pH changes. Then you won't need to check it daily, by then you'll know when you should check it. But that takes experience, and you only gain experience from doing.

As a Hint. If you get the General Hydroponics pH drops, the directions say to fill the vile 1/2 way and add 2-3 drops. What I do is fill the vile about 1/6 and use 1 drop. In other words, instead of using 3 drops, I use 1/3 the water and only one drop. you get the exact same color, just less water. Don't worry you don't need to be exact measuring, and it's easy to read the colors. In fact If you look on the right side of this section of this page pH adjusters, I created a visual color scale. I did the typical 1/2 vial and 3 drops for the pictures so it's bigger. But I only need 1/3 the water and one drop to test pH like I mentioned.

Does adding the fertilizer change the pH.

It can, That depends on the pH of the water, the mineral salts already in the water, and the specific composition of the nutrients. As well as pH buffers in the nutrients. Most commercial nutrients for hydroponics have pH buffers. The buffers help keep the pH stable longer. If your waters starting pH isn't that far off, the buffers usually wind up making the pH perfect at 6.0. On the other hand I have used nutrients that drooped the pH down to below 4.0. So it just depends. You'll eventually learn how your specific nutrients affect the pH.

After the nutrient mix is created, how often does the pH need to be retested and re-adjusted?

Again I would recommend any new grower check pH every day until they become experienced with it. When things are going right, typically the pH should remain stable for a good week or more. But things like the actual water volume relative to plant size, how big the plants are and how much water the plants are drinking up will quickly affect pH. Again, that's part of the experience I mentioned. I wrote this article What size reservoir do I need that will help explain how the water volume affects nutrients and pH swings.

Is there a way I can determine when to add more nutrient as the plants consume the nutrients?

EXPERIENCE....EXPERIENCE....EXPERIENCE....
Watching your plants and paying attention to changes will tell you exactly when the nutrients are depleted. New baby leaves will start turning light green/yellow. That means the nutrients are depleted. There could be other reasons for leaves turning yellow, but experience will tell you if the yellowing may be a result of other issues, or it's just time to change the nutrients. Water volume relative to plant size, and water uptake are factors that affect how long the nutrient solution will last. Again those factors are explained in the "What size reservoir do I need" article I posted a link to above. Observation and paying attention to your plants daily is how you gain experience.

I assume there is a way to test for the nutrient concentration.

That is called a TDS/PPM/EC meter. While some people can't live withough't a TDS/PPM/EC meter, to me their just a fun toy to have if you have the money to spend. The one thing I want them to be able to do, they cant do, so I don't bother using them. Plants don't take up nutrients evenly, they take what they need and leave the rest. This means that some nutrients are used up faster than others. The TDS/PPM/EC meter cant tell you which ones are in the water and what concentrations each are in (witch is the one thing I want them to do). That means some elements are depleted more than others.

When you use a TDS/PPM/EC meter to adjust and bring back up nutrient concentrations, your adding a balanced nutrient to an unbalanced nutrient solution. So now the nutrients that were depleted most are still somewhat depleted, and the ones that weren't used as much are now in excess. Because the TDS/PPM/EC meter cant tell you what is in the water, only the total combined value of everything combined, it cant tell you how unbalanced it is. If you just keep adding nutrients back to bring the TDS/PPM/EC meter reading to a specific level, over time the nutrient solution will become more and more unbalanced to the point where the nutrients the plants use most are very deleted, and the others are at toxic levels. Even though your TDS/PPM/EC meter readings are in the right range. That's why I don't bother with them. A good TDS/PPM/EC meter will cost over $100, and I can buy enough nutrients to make 5,000 gallons of nutrients for that. So I'd rather have the nutrients to grow plants with than neat toys.

About how long would the nutrient last before throwing out the mix and starting with a new batch?

Again, EXPERIENCE....EXPERIENCE....EXPERIENCE.... But in general typically 1-4 weeks. It has everything to do with water volume to plant ratios. As well as environmental conditions. That's why I wrote the article What size reservoir do I need to help explain those factors, and explain how water and plant size are related.