richdavis

optimum ph

17 posts in this topic

My system has been cycled for about a week now. In one of my beds i have a few plants that are yellowing, and a few of the lower leaves have died. The PH has climbed to 7.8- 8.0, and from what i have gathered i believe the PH recomendation is 6.8- 7.2, and i was wondering what to use to lower this without chemicals. Other than this everything seems to be great, and i wanted to thank everyone for the help. I have had to raise my lights 2" a day for the past 4 days. plants seem to be growing well other than the lower leaf issue, and a little yellowing. If this helps My nitrates have been from 10- 20 and 20- 40 ppm depending on when i test the water. I am in the process of builing a new bed, and adding a radial flow filter. Thanks again, Rich.

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Have you tried chelated iron or maxicrop with iron?

Peat moss is supposed to be an organic way to lower the ph, but I have not tried it, I use muriatic acid now after fighting ph bounce with vinegar. A drop or two of muriatic acid goes a long way.

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I cannot find chelated iron, or a good answer on the maxicrop products i have found. No one has the maxicrop original seaweed extract, and i am not sure if the one's they have are ok for AP. There are no hydroponic stores here that are knowledgable with AP. So it has been very confusing. I cannot order online, so the maxicrop product i did find is liquid seaweed, with and without iron. Is this the same as the original seaweed extract? Is muriatic acid any different than PH down? Thanks, Rich.

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Ph down is normally phosphoric acid, but can be something else. Phosphorus levels are generally high in ap, so adding more is not usually required. Muriatic acid is generally sold in hardware stores and is hydrochloric acid, it is very strong, so add a little to a bucket of water and then add from the bucket to your system. It will drop the ph some at first, but a lot of chemical reactions will take place, so wait several hours and recheck the ph before adjusting again. A good rule of thumb is adjust only once a day.

I have used the liquid seaweed from an off brand and it worked well for me, but I can't say how well the brand in your locale will work. I also add epsom salt about 1 lb per 4000 gallons. I suspect the liquid seaweed will work just fine, but you may want to add a small amount over several days, rather than a lot at one time.

I recommend you start with either one or the other , either adjust ph or add the seaweed, but I would not do both in the same week, so as to minimize stress. It is very easy to stress your bacteria and fish by adjusting the ph and it will self adjust in time, so go slowly a little bit every few days if attempting to adjust your ph.

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Hi Rich,

All of the products that Maxicrop make are listed on this website. It also has a contact number so that you can identify your local stockist. If you don't have a stockist near you, order it online.

Any of the plain seaweed products (including the one with iron) are fine. Since you don't use a lot of the stuff, you will get away with the home range of products.

Your system will take some time to settle down......and your high pH is probably locking out some nutrients. It will drop of its own accord over time.....or you can use muriatic (hydrochloric) acid.....sparingly.....to bring it down. The key is to make small adjustments over a period of days.

Don't be tempted to add a bit more when you don't see things happening immediately.....remain self-disciplined and give yourself a day or two to allow things to settle between each dose of anything.

Familiarise yourself with the procedure for adding acid to water......never add water to acid - it will produce an explosive reaction.

Gary

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Ok, great. I appreciate the advice from both of you. I think i will start with the seaweed with iron a little bit at a time, and just keep an eye on my PH. It get's confusing at the store when you are talking to people who know hydroponics, but not AP. They tend to make me double guess myself. I will try to let the PH drop on it's own. thanks again, Rich.

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I have used the liquid seaweed from an off brand and it worked well for me, but I can't say how well the brand in your locale will work. I also add epsom salt about 1 lb per 4000 gallons. I suspect the liquid seaweed will work just fine, but you may want to add a small amount over several days, rather than a lot at one time.

I bought some liquid seaweed (general organics, I think) and only used it as a foliar spray. Would you recommend adding this to the water as well? Also, why the epsom salt? I use it in the soil around my peppers, but hadn't thought/heard of adding it to the AP water.

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I've added the liquid seaweed and saw a huge spurt in growth. I do not know if there is variation in ingrediants as its not regulated here and they do not have to list ingrediants, so contents can vary from brand to brand. I added 1 pint to my 4000 gallon system. The Epsom salt is primarily used as a source of magnesium which is normally lacking in fishfood.

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Is that rate 1 pint/4000 gallon based on the recommended dilution on the product or your own knowledge? Just wondering whether to scale accordingly (my system is around 200 gal) or just follow the manufacturer's recommendations on what I have. Also, my system is salted to about 1ppm with aquarium salt, adding the epsom salt in small quantities shouldn't pose any issues, right?

Rich,

Sorry if it seems that I am hijacking your thread, but I figured that these questions are in line with the solution to your questions. If not, my apologies.

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Came to that ratio due to: mainly it came in a 1 pint bottle. Added 1/2 and didn't notice any change, so added the rest and my tomato plant took off and the everything started growing well.

The ratio of epsom salt should not have a practical effect at that level on total salinity. Magnesium salts will be used by the plants and taken out of the system as the plant grows, sodium salts have very little uptake except with certain plants, spinach is one, and levels stay relatively constant.

I don't think this is the perfect panacea, but it's the best combination I've come up with or read about to date.

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Thanks Ravnis. Will give it a try since I'm always up for a little accelerated plant growth/health.

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Hello all.

I too struggle with not only what to put into my water but in what amounts. Isn't there a more definitive guide based on science that can answer these questions? I can't even figure out if I am feeding my Talapia too much or too little or too often.

This is probably one of the biggest hurdles for new guys like me.

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just on phosphate levels being generally high, I've been measuring mine and generally struggle to get a reading.  Even when heavily feeding trout when my nitrate levels go up to 400ppm, I still struggle to see 2ppm on phosphate.

 

I believe that they may not be as high as they once were due to phosphate levels being lowered in AQ feed pellets to address AQ pollution issues.  Also most phosphate in fish poo is in solid form so needs to be mineralised, so levels will be lower in young systems.  I don't mean to hijack the post as this has not much to do with ph, though felt it was important to address.  My impression is that it is commonly believed that phosphate levels are high in AP systems, though not many people measure them.  My experience has certainly not corroborated the belief.

Ph down is normally phosphoric acid, but can be something else. Phosphorus levels are generally high in ap, so adding more is not usually required. Muriatic acid is generally sold in hardware stores and is hydrochloric acid, it is very strong, so add a little to a bucket of water and then add from the bucket to your system. It will drop the ph some at first, but a lot of chemical reactions will take place, so wait several hours and recheck the ph before adjusting again. A good rule of thumb is adjust only once a day.

I have used the liquid seaweed from an off brand and it worked well for me, but I can't say how well the brand in your locale will work. I also add epsom salt about 1 lb per 4000 gallons. I suspect the liquid seaweed will work just fine, but you may want to add a small amount over several days, rather than a lot at one time.

I recommend you start with either one or the other , either adjust ph or add the seaweed, but I would not do both in the same week, so as to minimize stress. It is very easy to stress your bacteria and fish by adjusting the ph and it will self adjust in time, so go slowly a little bit every few days if attempting to adjust your ph.

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Interesting about your phosphate levels being low, maybe the trout feed is low on phosphate as compared to catfish/tilapia feed?  I generally read 4-6 ppm the times I tested it to off the scale.

 

Strider, there have been members that measured levels and growth response.  The one that did the most besides Paul left to start his own forum and I've not heard more from him in a few years.  I suspect hydro operators have done work in this area and probably found optimums based on crop being grown. Each plant will have it's optimum range depending on whether it is a leafy crop vs fruiting crop.  I remember reading about some members doing BRIX testing too , but have not seen much in the way of follow up on that posted.

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One (of many) basic hydro guides.. in terms of pH (and EC/CF)

 

VEGETABLES          PH          CF          PPM

Artichoke           6.5-7.5      8-18      560-1260

Asparagus          6.0-6.8     14-18     980-1260

Beans                6.0           20-40     1400-2800

Beetroot            6.0-6.5      8-50      1260-3500

Broad beans       6.6-6.5      18-22     1260-1540

Broccoli             6.0-6.8      28-35     1960-2450

Brussell sprouts   6.5           25-30     1750-2100

Cabbage            6.5-7.0      25-30     1750-2100

Capsicum           6.0.6.5      18-22     1260-1540

Carrots              6.3           16-20      1120-1400

Cauliflower         6.5-7.0       5-20      1050-1400

Celery               6.5            18-24     1260-1680

Cucumber          5.5            17-25     1190-1750

Eggplant            6.0            25-35     1750-2450

Endive               5.5            20-24     1400-1680

Fodder               6.0           18-20      1260-1400

Garlic                 6.0           14-18      980-1260

Leek                  6.5-7.0      14-18      980-1260

Lettuce              6.0-7.0      8-12       560-840

Marrow               6.0           18-24     1260-1680

Okra                  6.5            20-24     1400-1680

Onions               6.0-6.7      14-18      980-1260

Pak choi             7.0            15-20     1050-1400

Parsnip              6.0            14-18      980-1260

Peas                 6.0-7.0        8-18      980-1260

Pepino               6.0-6.5       20-50     1400-3500                        

Potato               5.0-6.0       20-25     1400-1750

Pumpkin             5.5-7.5       18-24     1260-1680

Radish               6.0-7.0       16-22      840-1540

Spinach             6.0-7.0       18-23      1260-1610

Silverbeet          6.0-7.0       18-23      1260-1610

Sweet corn        6.0             16-24      840-1680

Sweet potato     5.5-6.0       20-25      1400-1750

Taro                 5.0-5.5        25-30     1750-2100

Tomato             6.0-6.5        20-50     1400-3500

Turnips             6.0-6.5        18-24      1260-1680

Zucchini            6.0             18-24      1260-1680

HERBS

Basil                 5.5-6.5       10-16       700-1120

Chicory             5.5-6.0       20-24       1400-1600

Chives              6.0-6.5       18-22       1260-1540

Fennel              6.4-6.8       10-14       700-980

Lavender           6.4-6.8       10-14      700-980

Lemon balm       5.5-6.5       10-16       700-1120

Marjoram           6.0            16-20       1120-1400

Mint                 5.5-6.0       20-24       1400-1680

Mustard cress    6.0-6.5       12-24       840-1680

Parsley             5.5-6.0        8-18        560-1260

Rosemary          5.5-6.0       10-16       700-1120

Sage                5.5-6.5       10-16       700-1120

Thyme                5.5-7.0        8-16        560-1120

Watercress       6.5-6.8        4-18        280-1260

Edited by RupertofOZ (see edit history)
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Interesting about your phosphate levels being low, maybe the trout feed is low on phosphate as compared to catfish/tilapia feed?  I generally read 4-6 ppm the times I tested it to off the scale.

 

Strider, there have been members that measured levels and growth response.  The one that did the most besides Paul left to start his own forum and I've not heard more from him in a few years.  I suspect hydro operators have done work in this area and probably found optimums based on crop being grown. Each plant will have it's optimum range depending on whether it is a leafy crop vs fruiting crop.  I remember reading about some members doing BRIX testing too , but have not seen much in the way of follow up on that posted.

Thanks Ravnis. And excuse my hyjack of your thread Rich, but it seemed we are both looking for the same answers so I thought I would chime in with some questions too.  I have done hydroponics for many years, but my issue is with the added element of the fish and what is safe and what is needed.  I guess if I knew what the fish do not provide I could suppliment. But I have not even figured out how much to feed the critters.  Maybe I am under feeding them?  

Anyway, I have another thread so I will just bother people over there...sorry Rich.

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I dug and found one of the old threads that gave some info on levels in a system as well as a test kit source.  The test kit is not cheap by any means, but would be worthwhile in a large system. 


 


http://aquaponicsnation.com/forums/topic/802-utah-system-part-1-beginnings/page-5


 


Paul , AKA earthangroup, posted some numbers of one of his systems on his site that should make a  starting comparison.  If you haven't visited his site, it's well worth a look as well.


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